In the Quran, Muhammad told of the tribes of Gog and Magog, which he said were kept back by a wall of solid metal built by Dhu al-Qarnayn (Surah 18:92-100) - who is Alexander the Great. This story dates back to at least the first century, as Josephus (37-100 CE) mentions Alexander building an iron wall between two mountains to hold back the Scythians (The Wars of the Jews, Book 7, Chapter 7), and Josephus identifies the Scythians with "Magogites" (Antiquities of the Jews - Book 1, Chapter 6).
Modern Muslims will typically attempt to deny that this is Alexander the Great, because like nearly every famous historical figure, Muhammad portrays him as Muslim in the Quran, which was definitely not true of Alexander the Great historically. Alexander followed ancient Greek religion, and identified himself as the son of Zeus-Ammon, a combination deity of the Greek god Zeus and the Egyptian god Amun.
Of these tribes, Muhammad also teaches that they will be held at bay until the end times, in which they will rush down and destroy most of civilization (Surah 18:98-100, 21:95-97).
In the Hadith, also, Muhammad spoke of Gog and Magog and the miraculous wall holding them back, saying:
Sahih al-Bukhari 3598
"Woe to the Arabs because of evil that has come near. Today a hole has been made in the wall of Gog and Magog as large as this" - pointing with two of his fingers making a circle.
This is also narrated in Sahih al-Bukhari 3346-47, 5293, 7059, 7135-36, and Sahih Muslim 2880a-d, 2881, 2937a. Additionally, there is a narration stating that every day they try to dig through the wall, but God repairs the wall each time (Sunan Ibn Majah 4080).
Muhammad also expands on the details of their final conquest in the Hadith, saying that when they arrive, there will be so many of them that they will be able to drink the entire Lake of Tiberias (Sahih Muslim 2937a, Sunan Ibn Majah 4075), and that Muslims will be able to use their bows, arrows, and shields for firewood for 7 years afterward (Sunan Ibn Majah 4076).
So, Muhammad claimed that there are vicious, savage tribes existing somewhere on earth, contained behind a wall of solid metal built by a Muslim man thousands of years ago. However, in modern times, the entire earth can be seen with satellites, and there is no wall, and no vast, savage tribes waiting to destroy all peoples of the earth, each day held back by a miraculous repair to Dhu al-Qarnayn's wall. Therefore, a large part of Muhammad's end times doctrine is centered on tribes and a giant wall which - unlike Muhammad's audience in the 7th century - anyone today can verify do not exist.
Additionally, Muhammad had many other failed/false prophecies, such as his prophecy that the world would end within 100 years (Sahih al-Bukhari 116, 564, Sahih Muslim 2538a, 2539), or within the life of a young slave in his presence (Sahih al-Bukhari 6167), or within the lifespan of an Ansari child (Sahih Muslim 2952, 2953a-c). He frequently claimed that the Last Hour was very near (Sahih al-Bukhari 2222, 3448, 4936, 5301, 6503-05, Sahih Muslim 155a, 867a, 2950, 2951b-e). He even was open to a young man named Ibn Sayyad being the Dajjal, which is an end times figure in Islam (Sahih al-Bukhari 3055, Sahih Muslim 169d, 2924a-b, 2925, 2930a-c, 2931), even spying on him (Sahih al-Bukhari 3056-57, Sahih Muslim 169d, 2930a-c, 2931), and causing much trouble for him (Sahih Muslim 2927a-c, 2929).
So, one can observe what Muhammad taught about the future, and conclude that he was definitely a false prophet, and not someone sent from God.
A surprising amount of Muhammad's "revelations" are easy to see as things that he himself just wanted to say, placed into the mouth of "God" by him, to serve his own purposes.
For instance:
These aren't revelations from God. These are instances of a self-serving man putting his own thoughts and desires into the mouth of God.
In the Quran, Muhammad declared that some of God's teachings may be replaced with equivalent or better ones later on (Surah 2:106, 16:101). If the Quran were truly God's eternal word to mankind, one would think a provision could simply be given in the original verse (e.g., do so until such-and-such event), rather than a messy process of giving unqualified revelations and later revoking them.
One instance of an "abrogated" revelation would be a rule which dictated that if a woman had breastfed a man a certain number of times, they could not be married to each other. Muhammad first said that it was to be ten times, then changed it to five, then it was removed from the Quran altogether after Muhammad died:
Sahih Muslim 1452a
'A'isha (Allah be pleased with her) reported that it had been revealed in the Holy Qur'an that ten clear sucklings make the marriage unlawful, then it was abrogated (and substituted) by five sucklings and Allah's Apostle (ﷺ) died, and it was before that time (found) in the Holy Qur'an (and recited by the Muslims).
This is also narrated in Sahih Muslim 1452b, and Sunan an-Nasai 3307. Why would this teaching be modified? And, why would it be removed from the recitation of the Quran? Either this is part of God's eternal speech, or it is not. If it is not, why would it ever be recited as part of the Quran? If it is, why would God have people stop reciting it, while having them recite many other less consequential verses?
Another instance of abrogation relates to a moral judgement - the punishment for adultery. One of the Quran's prescribed punishments for an adulterous woman involves her being placed under house arrest for the rest of her life (Surah 4:15). Then, at some point, the punishment of stoning was prescribed, and Muhammad's companions testified that they carried it out, and recited it as part of the Quran (Sahih al-Bukhari 6829-30, Sahih Muslim 1691a, 1691c, Musnad Ahmad 197, 352, etc.). Then, the punishment of being flogged 100 times was given (Surah 24:2). Again, why would the punishment ever be changed at all, or "revealed" in a piecemeal way?
Finally, Muhammad's teaching on Mut'ah marriage (pleasure marriage) also changed over time. First, he allowed the practice:
Sahih al-Bukhari 4615
Narrated Abdullah:
We used to participate in the holy wars carried on by the Prophet (ﷺ) and we had no women (wives) with us. So we said (to the Prophet (ﷺ)). "Shall we castrate ourselves?" But the Prophet (ﷺ) forbade us to do that, and thenceforth he allowed us to marry a woman (temporarily) by giving her even a garment, and then he recited: "O you who believe! Do not make unlawful the good things which Allah has made lawful for you." (Surah 5:87)
So, Muhammad allowed his companions to "temporarily" marry a woman when they complained to him during "holy wars", by giving her something like a garment, and then the marriages would quickly be dissolved thereafter. This is essentially prostitution. Muhammad's endorsement of this practice is also narrated in Sahih al-Bukhari 5075, 5117-18, Sahih Muslim 1404a-c, 1405a-b, and Sunan Ibn Majah 1962.
Later, however, Muhammad went on to ban the practice, on the same day he banned the meat of domestic donkeys (Sahih al-Bukhari 4216, 5115, 5523, 6961, Sahih Muslim 1404b, 1405f, 1406a-l, 1407a-e). Or, according to some, it was allowed for Muhammad's entire life, and then Umar banned it (Sahih Muslim 1249, 1405c-e). Either way, the Sunni narrations are unanimous in stating that Muhammad allowed this practice during the early days of Islam, yet most now regard it as forbidden. But, why would that ever change?
These don't read as divine revelations. They read as someone making things up as he goes along, because he is not relaying messages from God, but instead inventing his own teaching and belief system.
In the Quran, Muhammad claimed to affirm the "Torah" and the "Gospel" (Surah 3:3-4, 5:43-47, 5:68), and clearly references characters and events from the only "Torah" and "Gospel" known to history. But, being very ignorant on the details of the Old/New Testaments, he proceeded to contradict and depart from what those texts taught on a host of doctrines, so now Muslims have to pretend that he affirmed a different and now lost Torah and Gospel which, conveniently, no one gets to see. Never mind that it is well known what each text looked like during the time of Muhammad (and long before him). Historical evidence does not matter to Muslims in this regard, because history refutes their clearly false religion, so they dismiss it.
For instance, in the Hebrew Bible, God is referred to as the "Father" of believers, who are said to be His "children", many times (Genesis 6:1-4, Exodus 4:22, Deuteronomy 14:1, 32:5-6: 2 Samuel 7:14, Job 1:6, 2:1, 38:7, Psalm 2:7, 2:12, 73:15, 89:26, Isaiah 43:6, 63:16, 64:8, Jeremiah 3:19-20, Hosea 1:10, Malachi 2:10). Likewise, in the New Testament, the concept of God being the Father of believers is a major theme (Matthew 6:9, 7:11, John 1:12, Galatians 3:26, 4:4-6: 1 John 5:1, etc.). But Muhammad decried the entire concept of God being a "father" (Surah 2:116, 5:18, 17:111, 19:35, 19:88-92, 21:26, 23:91, 37:151-52, 39:4, 43:81, 72:3), and specifically rejected Jews and Christians saying so (Surah 37:151-52). Additionally, the Quran predictably lacks any reference to God as the "Father" of believers.
The Torah says that the penalty for thievery is repayment (Exodus 22:1-12). Muhammad taught that it was cutting off the hands (Surah 5:38).
The Torah prohibits someone from remarrying their divorced spouse after that spouse has remarried and divorced someone else, and calls it an abomination (Deuteronomy 24:1-4). Muhammad taught that God required someone to remarry after a divorce, before remarriage to the original spouse was allowed (Surah 2:230) - the exact opposite teaching.
The Torah teaches that before a person is punished for a crime, testimony must be given by at least 2 or 3 witnesses (Deuteronomy 17:6, 19:15). Muhammad taught that one must have 5 total witnesses to accuse someone of adultery, and that one person may act as all five "witnesses" (Surah 24:4-9).
The Torah says that a person should not be beaten with over 40 lashes (Deuteronomy 25:3). Muhammad taught that people should be beaten with 100 lashes (Surah 24:2), or 80 lashes (Surah 24:4).
The Torah prohibits Israelites sleeping with married slave girls (Leviticus 19:20-22). Muhammad taught that Muslims can sleep with their married slave women (Surah 4:24).
Jesus, according to the Gospels, taught that marrying a divorced woman was prohibited, and called it adultery (Matthew 5:31-32, 19:3-9, Mark 10:2-12, Luke 16:18). Muhammad married a divorced woman, and said that his marriage to a divorced woman was revealed to him from God (Surah 33:37, cf. 66:5).
Jesus, according to the Gospels, taught that there will be no marriage in Heaven (Matthew 22:30, Mark 12:23-25, Luke 20:35). Muhammad frequently mentioned that a major aspect of Heaven involves being married to wives (Surah 2:25, 3:15, 4:57, 36:55-56, 37:48-49, 38:52, 43:70-71, 44:54, 52:20, 55:56, 55:70-74, 56:22-23, 56:35-37, 78:33).
And, this is omitting all the times Muhammad poorly retells a Bible story, and gets details wrong. For instance, Muhammad taught that Satan's temptation in the Garden of Eden resulted in the removal of Adam and Eve's clothing (Surah 7:27, directly contradicting Genesis 2:25, 3:7-11, 3:21), and the Garden of Eden was in Heaven rather than earth (Surah 2:36, contradicting Genesis 2:8).
Muhammad even claimed that Jesus said that he came to deliver "the glad tidings of an apostle who shall come after me, whose name shall be Ahmad" (Surah 61:6). No text known to human history puts these words in the mouth of Jesus, and none of the thousands of Christian texts before the time of Muhammad - written by people who would be highly interested in a coming "apostle" prophesied by their lord, Jesus - mention Jesus saying that an "apostle" named "Ahmad" would come after him.
Additionally, the Hebrew Bible contains all sorts of prescribed practices - sacrifices, holy days, and so on - which a pious Jew is compelled to perform. Christians, who profess to believe in the Hebrew Bible, yet do not do these practices, have explicit reasons that they give for why they did away with them (Acts 15:5-11, Galatians 3:24-25, etc.). Likewise, the Gospels prescribe certain practices for Christians, such as baptism (Matthew 28:19), and celebrating the Last Supper (Luke 22:19). Muhammad did none of these things, and instead appeared totally ignorant of them, never explaining why he did not do them, or why they were not binding on Muslims.
So, Muhammad absolutely did not affirm the "Torah" or "Gospel", as he claimed. If someone claims to affirm a corpus of texts, and is found to actually contradict them, that means they are a liar. Making claims such as the original texts having changed (known to be false in this case from well before the time of Muhammad), or affirming some unobservable, unseen "originals", could be done by anyone at any point in history, looking to teach any religious doctrine, or even an entirely new religion. It is meaningless, and proves nothing.
The Hajj pilgrimage is a major tenet of Islam, comprising one of the Five Pillars which every faithful believer is compelled to carry out. It involves circling a cubic building in Mecca (the Kaaba) seven times, kissing a black stone in the corner of that cubic building, and running between two hills, Safa and Marwa (Surah 2:158), among other things.
Muhammad claimed that the practice of circling the Kaaba began with (or even predated) Abraham (Surah 22:25-29), saying that God told him to "Call ˹all˺ people to the pilgrimage. They will come to you on foot and on every lean camel from every distant path" (Surah 22:27). However, unsurprisingly, there are no Jewish or Christian texts mentioning this practice of circling the Kaaba, or making a pilgrimage to Mecca, despite Muhammad insisting that the very founder of their religion was told by God to declare it as a universal practice.
Instead, there is a narration from a companion of Muhammad stating "During the Pre-Islamic period of Ignorance, the people used to perform Tawaf (circling) of the Kaaba" (Sahih al-Bukhari 1665, Sahih Muslim 1219b). Circling a cubic building in Mecca was not a Jewish practice, it was a practice of Arabian pagans who lived near Muhammad's hometown of Mecca. In keeping with his tendency to fabricate, he linked it to Abraham, despite there being no evidence whatsoever to support his claim, and all existing evidence refuting it.
Similarly, regarding walking between the two hills of Safa and Marwa, no Jew or Christian ever mentions the practice as being part of their religion, nor do they mention the two hills in question. However, Muhammad's companion said, "To run along the valley between two green pillars of Safa and Marwa was not Sunna, but the people in the pre-Islamic period of ignorance used to run along it" (Sahih al-Bukhari 3847, cf. 1643, 1648, 4496). Cutting one's hair - another practice associated with the Hajj - is also said by a companion of Muhammad to have been something people did prior to Islam when they went between these two hills (Sahih Muslim 1277a).
Finally, regarding kissing the Black Stone, this appears to be another relic of Arabian paganism, as one of Muhammad's companions testifies that prior to Islam, they used to worship stones, and carry stones with them to circle (Sahih al-Bukhari 4376).
Therefore these practices which Muhammad made part of his religion have no Abrahamic or Biblical origin. They are relics of his pagan environment in 7th century Arabia. Following them is just continuing the practices of Arabian pagans, which no one who wants to simply worship God would feel compelled to do on their own (esp. kissing a holy stone).
In the Quran, Muhammad taught that male seed comes from a place "stemming from between the backbone and the ribcage" (Surah 86:5-7). Of this passage, the Muslim commentator Ibn Kathir (1373 CE) said:
Tafsir Ibn Kathir - Surah 86:6-7
Then Allah says, (He is created from a water gushing forth.) meaning, the sexual fluid that comes out bursting forth from the man and the woman. Thus, the child is produced from both of them by the permission of Allah.
Due to this Allah says, (Proceeding from between the backbone and the ribs.) meaning, the backbone of the man and the ribs of the woman, which is referring to her chest. Shabib bin Bishr reported from `Ikrimah who narrated from Ibn `Abbas that he said, (Proceeding from between the backbone and the ribs.) "The backbone of the man and the ribs of the woman. It (the fluid) is yellow and fine in texture. The child will not be born except from both of them (i.e., their sexual fluids)."
Ibn Kathir understood this to refer to male and female seminal discharge. He says that the male semen comes from their backbone. Muhammad, at other times, has God use the phrase "while you were in the backbone of Adam" (Sahih al-Bukhari 3334) as a euphemism for "before you were born", so this is arguably consistent with Muhammad's overall teaching on reproduction. He then says that the woman's discharge is "yellow and fine in texture". This also comes directly from the traditional teachings of Muhammad, as he frequently taught that women have a thin yellow semen which mixes with a man's semen, and whoever's semen discharges first determines the looks of the baby (Sahih al-Bukhari 130, 3328-29, 3938, 4480, 6091, Sahih Muslim 311, 313a, 314b).
In the Hadith, Muhammad is also said to have said the following regarding germs and diseases:
Sahih al-Bukhari 3320
Narrated Abu Huraira:
The Prophet (ﷺ) said "If a house fly falls in the drink of anyone of you, he should dip it (in the drink) and take it out, for one of its wings has a disease and the other has the cure for the disease."
This is also narrated in Sahih al-Bukhari 5782, Sunan Ibn Majah 3505, and Sunan Abi Dawud 3844. It is verifiably false, and an extremely dangerous teaching.
If the wings of a fly are analyzed, it will not be the case that one will have a disease, and the other will have the corresponding cure for that disease. One wing of a fly is not always sterile and disease-fighting, with the other being only diseased and devoid of cure. And, adding the entire body of the fly to a drink has just exposed a person to millions and millions of bacteria, making the situation worse than it was when only a wing was submerged. This is a dangerous false teaching from someone who demanded that others obey him as if he were God (Surah 4:80, Sahih al-Bukhari 2956-57), and never question any of his judgments (Surah 4:65, 33:36, 49:1).
Additionally, in his commentary on Surah 36:38, Muhammad seemed to teach that the sun orbited the earth once per day, and that during the day, it was daytime for the whole earth simultaneously, indicating a flat-earth view.
For instance:
Sahih al-Bukhari 3199
Narrated Abu Dhar:
The Prophet (ﷺ) asked me at sunset, "Do you know where the sun goes (at the time of sunset)?" I replied, "Allah and His Apostle know better." He said, "It goes (i.e. travels) till it prostrates Itself underneath the Throne and takes the permission to rise again, and it is permitted, and then (a time will come when) it will be about to prostrate itself but its prostration will not be accepted, and it will ask permission to go on its course but it will not be permitted, but it will be ordered to return whence it has come, and so it will rise in the west. And that is the interpretation of the Statement of Allah: "And the sun Runs its fixed course For a term (decreed). That is The Decree of (Allah) The Exalted in Might, The All-Knowing." (Surah 36:38)
This is also narrated in Sahih al-Bukhari 4802-03, 7433, and Sahih Muslim 159a-d, and it is reiterated that this is Muhammad's commentary on Surah 36:38.
This appears to teach a flat-earth view of the world, wherein the sun "goes" somewhere at night, for all of the earth. In reality, the sun does not "go" anywhere at sunset, because it is always sunset somewhere on earth. So, it would not make sense to say the sun "goes" to prostrate under the throne of God during the nighttime, as it is always nighttime somewhere on earth, and so the sun would be in constant "prostration", making Muhammad's statement here rather meaningless.
Other times, Muhammad is recorded saying that one cannot pray when the sun is directly overhead, as that is "the time when the gates of Hell are opened and it is stoked up" (Sunan an-Nasai 572). He also forbade praying during the rising and setting of the sun, "for it rises between the horns of Satan" (Sahih Muslim 828b). Yet, it is always the case that the sun is rising, directly overhead, or setting, somewhere on earth, because it is round. Muhammad, from how he spoke of the sun, did not seem to understand this.
In the Quran, Muhammad frequently says something like the following:
Surah 6:125
125 Whoever Allah wills to guide, He opens their heart to Islam. But whoever He wills to leave astray, He makes their chest tight and constricted as if they were climbing up into the sky. This is how Allah dooms those who disbelieve.
This passage teaches that God actively guides certain people to faith, and also chooses to harden or not guide others. Similar passages include Surah 2:6-7, 4:143, 4:155, 6:25, 6:35, 6:39, 6:107, 6:149, 7:30, 7:178, 7:186, 10:19, 10:99-100, 11:118, 13:27, 13:31, 14:4, 16:9, 16:37, 16:93, 32:13, 35:8, 36:7-10, and 42:8.
Muslims who are uncomfortable with this teaching will typically respond that God only allows people to go astray who wish to go astray themselves, and guides those who already seek Him, and that is essentially all predestination is in Islam. However, that is definitely not the Islamic doctrine of predestination - that is the exact opposite of predestination, and there would be no reason for any discussion of predestination (Qadar) with respect to Islam if that were all Islam taught.
Muhammad actually taught that the reason someone wills to do good or seek God in the first place is God causing them to do so:
Surah 76:29-30
29 Surely this is a reminder. So let whoever wills take the ˹Right˺ Way to their Lord.
30 But you cannot will ˹to do so˺ unless Allah wills. Indeed, Allah is All-Knowing, All-Wise.
The same thing is taught in Surah 81:27-29. Additionally, Muhammad explicitly teaches that no one can believe without God's will enabling them to do so, when speaking on why all people don't believe (Surah 10:99-100). In Islam, if a person does well, it is because God predestined them to do well, and if they do evil, it is because God predestined them to do evil. This will become very clear by examining the Hadith on this topic.
In one narration, two men ask Muhammad about whether one's fate is determined by destiny or the fact that they chose to heed or not heed prophets who are sent to them, and Muhammad says that it is determined by destiny, an answer the implications of which (earlier in the Hadith) made the questioner "greatly disturbed":
Sahih Muslim 2650
Two men of the tribe of Muzaina came to Allah's Messenger (ﷺ) and said: Allah's Messenger, what is your opinion on what the people do today in the world, and strive for? Is it something decreed for them or preordained for them, or will their fate in the Hereafter be determined by the fact that their Prophets brought them teaching which they did not act upon, and thus they became deserving of punishment? Thereupon, he said: Of course, it happens as it is decreed by Destiny and preordained for them, and this view is confirmed by this verse of the Book of Allah, the Exalted and Glorious: "Consider the soul and Him Who made it perfect, then breathed into it its sin and its piety" (Surah 91:8).
Muhammad also, when asked about destiny, explained that the reason someone does good or evil is that good or evil works have been made easier for them based on their destiny:
Sahih Muslim 2647a
Ali reported:
We were in a funeral in the graveyard of Gharqad when Allah's Messenger (ﷺ) came to us and we sat around him. He had a stick with him. He lowered his head and began to scratch the earth with his stick, and then said: There is not one amongst you whom a seat in Paradise or Hell has not been allotted and about whom it has not been written down whether he would be an evil person or a blessed person. A person said: Allah's Messenger, should we not then depend upon our destiny and abandon our deeds?
Thereupon he said: Acts of everyone will be facilitated in that which has been created for him, so that whoever belongs to the company of the blessed will have good works made easier for him, and whoever belongs to the unfortunate ones will have evil acts made easier for him.
This is also narrated in Sahih al-Bukhari 6596, 6605, and Sahih Muslim 2647c, 2648a, 2649a. Here Muhammad explains the mechanism that gives the illusion of piety or wickedness - a person's pre-ordained destiny operating on them. Other narrations bolstering this include one given in Sahih al-Bukhari 6594, and Sahih Muslim 2643a, 2644, where Muhammad says that a person's deeds are written before they are born, and they are essentially helpless but to carry out their destiny. The whole context of Muhammad's teaching demonstrates that this is not mere foreknowledge, but rather, predestination.
Additionally, there is a narration in which Muhammad is at the funeral of a child with his wife, Aisha. Aisha says that the child is surely in Heaven, because it was too young to sin. Muhammad corrects her, and says that the child may actually be in Hell, because those who go to Hell are created for Hell while they are yet in their father's loins:
Sahih Muslim 2662c
A'isha, the mother of the believers, said that Allah's Messenger (ﷺ) was called to lead the funeral prayer of a child of the Ansar. I said:
Allah's Messenger, there is happiness for this child who is a bird from the birds of Paradise, for it committed no sin, nor has he reached the age when one can commit sin. He said: A'isha, peradventure, it may be otherwise, because God created for Paradise those who are fit for it while they were yet in their father's loins, and created for Hell those who are to go to Hell. He created them for Hell while they were yet in their father's loins.
This is also narrated in Sahih Muslim 2662b, Sunan an-Nasai 1947, Sunan Ibn Majah 82, and Sunan Abi Dawud 4713. It shows that Muhammad taught that a person's destiny was fixed from birth, regardless of whether they appeared to deserve any one particular fate. It is out of their control, decreed by God, according to Muhammad.
So, one reason Islam is nonsense would be that it is ultimately inconsequential, as God, according to Muhammad, has already fixed each person's destiny, and whether they appear to desire good or evil is really just that predetermined fate working itself out.
Islam is nonsense because it was founded on a false prophet, who taught that the end of the world was imminently near during the 7th century. He invented revelations to suit himself, modified his own revelations later on as the opportunity arose, fabricated nearly all of the religious history he attempted to teach, and contradicted the "revelations" of those who he claimed to be following.
Islam is not the religion of simply worshipping God. That is called "Theism". Instead it is a convoluted offshoot of Judaism (an already false religion), with scores of rules, rituals, and practices compiled at the whim of a deeply ignorant false prophet in 7th century Arabia.