In the Quran, Muhammad teaches that a Muslim man may marry up to four women, and have intercourse with as many slave girls as he has besides - even if those slave girls are married:
Surah 4:3
3 If you fear you might fail to give orphan women their ˹due˺ rights ˹if you were to marry them˺, then marry other women of your choice - two, three, or four. But if you are afraid you will fail to maintain justice, then ˹content yourselves with˺ one or those ˹bondwomen˺ in your possession. This way you are less likely to commit injustice.
Surah 4:24
24 Also ˹forbidden are˺ married women - except ˹female˺ captives in your possession. This is Allah's commandment to you. Lawful to you are all beyond these - as long as you seek them with your wealth in a legal marriage, not in fornication. Give those you have consummated marriage with their due dowries. It is permissible to be mutually gracious regarding the set dowry. Surely Allah is All-Knowing, All-Wise.
The second passage above teaches that it is permissible to rape female captives, even if they are married, and it is reiterated in Surah 23:5-6, 33:50, and 70:29-30. The background of this verse is given in Sahih Muslim 1456a and Sunan Abi Dawud 2155, where it is shown to be in context to assuaging the shyness of his companions to have intercourse with women that their army had just taken captive, whose husbands were still alive.
The first passage above establishes the four-wife limit, and notice that you can only marry four women so long as you treat all of your wives equally. Muhammad himself did not do this, as we read a Hadith in which it was well-known that he favored Aisha above all the rest of his wives, and that his other wives banded together to complain about this (Sahih al-Bukhari 2581).
He also made an agreement with one of his wives, Sauda, when she became old and fat, that rather than divorcing her, he would skip her day and spend it with Aisha instead (Sahih al-Bukhari 1680, 4795, 5212, Sahih Muslim 1463a, Mishkat al-Masabih 3237). This unequal arrangement led to another passage being "revealed", stating that unequal treatment is actually fine, so long as it's agreed by both husband and wife (Surah 4:128-130). Mark this as an instance of Muhammad justifying his sin and violation of his own "revelations".
In addition, we read in the Hadith that Aisha herself noticed how "Allah" seemed so keen to fulfill Muhammad's every sexual desire, after he "revealed" to Muhammad that yet more of his unequal treatment of his wives was completely fine:
Sahih al-Bukhari 4788
Narrated Aisha:
I used to look down upon those ladies who had given themselves to Allah's Messenger (ﷺ) and I used to say, "Can a lady give herself (to a man)?" But when Allah revealed: "You (O Muhammad) can postpone (the turn of) whom you will of them (your wives), and you may receive any of them whom you will; and there is no blame on you if you invite one whose turn you have set aside (temporarily).' (Surah 33.51) I said (to the Prophet), "I feel that your Lord hastens in fulfilling your wishes and desires."
The above is also narrated in Sahih Muslim 1464a-b. Muhammad is neglecting his wives to sleep with other women - either slave girls, or certain of the other wives. Aisha calls him out on this, and he receives a suitable "revelation" permitting it. And, this "revelation" is part of the "eternal word of God", and so it is still preserved for us to see in the Quran (Surah 33:51). Aisha remarks on how swiftly "Allah" fulfilled Muhammad's desires. Exactly.
Muhammad also received a "divine revelation" that he - and he alone - could break the four-wife limit and marry as many women as he wanted:
Surah 33:50
50 O Prophet! We have Made lawful to thee Thy wives to whom thou Hast paid their dowers; And those whom thy Right hand possesses out of The prisoners of war whom God has assigned to thee; And daughters of thy paternal Uncles and aunts, and daughters Of thy maternal uncles And aunts, who migrated (From Mecca) with thee; And any believing woman Who dedicates her soul To the Prophet if the Prophet Wishes to wed her; — this Only for thee, and not For the Believers (at large); We know what We have Appointed for them as to Their wives and the captives Whom their right hands Possess; — in order that There should be no difficulty For thee. And God is Oft-Forgiving, Most Merciful.
So, we learn that you must have only up to four wives - unless you're Muhammad. And, you must treat them equally - unless you're Muhammad. And, by the way, you are allowed to marry someone else's widows after they die (Surah 2:234) - unless they are Muhammad's widows (Surah 33:53). Isn't it incredible how often the one giving the "revelations" finds exceptions for himself?
What are some issues with these teachings, beyond Muhammad's evident hypocrisy? The first would be the extreme perversion of sleeping with married slave girls, something that the Bible which Muhammad claimed to confirm explicitly said not to do (Leviticus 19:20-22). This is a great formula for spreading immorality, perversion, and disease, with slave girls being treated as tantamount prostitutes, even if they are married.
The second problem is that four wives does not work, either practically, or demographically. Practically, the wives will grow to hate each other (see the story of Rachel and Leah in Genesis 29-35), and unequal treatment is inevitable, as Muhammad himself not only taught (Surah 4:129), but also personally demonstrated. Demographically, God made roughly 50% of babies male, and 50% female. But, if every man is responsible, and able to ideally marry four women, what you have is a model that does not work. It creates a huge shortage of marriageable women, and results in left-over men. Nature testifies that one woman and one man is God's will, precisely as He said (Genesis 2:24: 1 Timothy 3:2, 3:12, Titus 1:6).
In the Quran, Muhammad teaches that you must have five total witnesses to accuse any woman of adultery, otherwise you will be whipped eighty times:
Surah 24:4-9
4 Those who accuse chaste women ˹of adultery˺ and fail to produce four witnesses, give them eighty lashes ˹each˺. And do not ever accept any testimony from them—for they are indeed the rebellious—
5 except those who repent afterwards and mend their ways, then surely Allah is All-Forgiving, Most Merciful.
6 And those who accuse their wives ˹of adultery˺ but have no witness except themselves, the accuser must testify, swearing four times by Allah that he is telling the truth,
7 and a fifth oath that Allah may condemn him if he is lying.
8 For her to be spared the punishment, she must swear four times by Allah that he is telling a lie,
9 and a fifth oath that Allah may be displeased with her if he is telling the truth.
But notice above, a husband may act as all four of his own additional witnesses, by saying "She did it, she did it, she did it, she did it, and may Allah condemn me if I'm lying".
However, this may be countered with the wife saying "I didn't do it, I didn't do it, I didn't do it, I didn't do it, and may Allah be displeased with me if I did". I don't know about you guys, but this really seems like divine, rational justice to me.
And once again, this explicitly contradicts what the Word of God says on the matter (Deuteronomy 17:6, 19:15).
In the Quran, it's taken for granted that divorce is permissible, and no requirement is ever listed that must be met in order for divorce to become permissible (Surah 2:227-237).
Instead, all that must be said is "Talaq" (I divorce you), three times. After the third time, the marriage may not be reconciled unless the woman gets married to someone else, and then divorces that other person as well (Sahih al-Bukhari 5261, Sahih Muslim 1471b):
Surah 2:230
230 So if a husband divorces his wife ˹three times˺, then it is not lawful for him to remarry her until after she has married another man and then is divorced. Then it is permissible for them to reunite, as long as they feel they are able to maintain the limits of Allah. These are the limits set by Allah, which He makes clear for people of knowledge.
The above teaching makes absolutely no sense. What kind of person thinks that it is a good idea to disallow reconciliation unless the woman goes out and has intercourse with someone else first? That makes no sense whatsoever, and is explicitly condemned in the actual Word of God:
Deuteronomy 24:1-4
1 When a man hath taken a wife, and married her, and it come to pass that she find no favour in his eyes, because he hath found some uncleanness in her: then let him write her a bill of divorcement, and give it in her hand, and send her out of his house.
2 And when she is departed out of his house, she may go and be another man's wife.
3 And if the latter husband hate her, and write her a bill of divorcement, and giveth it in her hand, and sendeth her out of his house; or if the latter husband die, which took her to be his wife;
4 Her former husband, which sent her away, may not take her again to be his wife, after that she is defiled; for that is abomination before the LORD: and thou shalt not cause the land to sin, which the LORD thy God giveth thee for an inheritance.
Above gives the only provision for divorce in the Word of God - a woman misrepresenting her virginity to a man, so that the marriage is immediately annulled (Deuteronomy 22:13-21) - and it calls Muhammad's prescription an "abomination", as is reiterated in Jeremiah 3:1.
Anyone can look at the above, and see that the Bible's rules make sense, and the Quran's don't. All Muhammad's bogus rules serve to do is cause more disease, divorce, broken families, illegitimate children, and corruption.
Also, to show how much he "affirmed" the Bible (Surah 3:3, 5:68, etc.), Muhammad permitted remarriage of divorced people, something that God explicitly and repeatedly says is adultery in Scripture (Matthew 5:32, 19:9, Mark 10:11-12, Luke 16:18).
Moreover, the Quran contains a bizarre passage in which Muhammad disparages his wives, and threatens to divorce them, boasting that Allah would just give him new, better wives if he did:
Surah 66:1-5
1 O Prophet! Why do you prohibit ˹yourself˺ from what Allah has made lawful to you, seeking to please your wives? And Allah is All-Forgiving, Most Merciful.
2 Allah has already ordained for you ˹believers˺ the way to absolve yourselves from your oaths. For Allah is your Guardian. And He is the All-Knowing, All-Wise.
3 ˹Remember˺ when the Prophet had ˹once˺ confided something to one of his wives, then when she disclosed it ˹to another wife˺ and Allah made it known to him, he presented ˹to her˺ part of what was disclosed and overlooked a part. So when he informed her of it, she exclaimed, “Who told you this?” He replied, “I was informed by the All-Knowing, All-Aware.”
4 ˹It will be better˺ if you ˹wives˺ both turn to Allah in repentance, for your hearts have certainly faltered. But if you ˹continue to˺ collaborate against him, then ˹know that˺ Allah Himself is his Guardian. And Gabriel, the righteous believers, and the angels are ˹all˺ his supporters as well.
5 Perhaps, if he were to divorce you ˹all˺, his Lord would replace you with better wives who are submissive ˹to Allah˺, faithful ˹to Him˺, devout, repentant, dedicated to worship and fasting—previously married or virgins.
From Sunan an-Nasai 3959, we learn Aisha and Hafsa were mad at Muhammad for sleeping with his slave girl, and that caused this verse to be revealed. This "revelation" is yet more evidence that Muhammad had a complete lack of regard for marriage, and also that divorce to him was a perfectly valid thing to threaten his wives with. What wickedness.
I have an entire article dedicated to the topic of child marriage in Islam, entitled Islam's Blatant Approval of Child Marriage and Intercourse, which demonstrates that Muhammad not only allowed his followers to marry prepubescent children, but also did this himself to his youngest wife Aisha, whom he had intercourse with when she was nine (lunar) years old:
Sahih al-Bukhari 5133
Narrated 'Aisha:
That the Prophet (ﷺ) married her when she was six years old and he consummated his marriage when she was nine years old, and then she remained with him for nine years (i.e., till his death).
Please refer to the aforementioned article for a detailed look at this immoral, corrupt practice within Islam.
"Temporary marriage" in return for a "dowry", also known as prostitution, was allowed by Muhammad when Islam began:
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."
The above shows us that Muhammad appealed to a verse in the Quran to justify his allowance of "temporary marriage", which is textbook prostitution in every sense except in name only:
Surah 5:87
87 O believers! Do not forbid the good things which Allah has made lawful for you, and do not transgress. Indeed, Allah does not like transgressors.
Muhammad's endorsement of this practice is also recorded in Sahih al-Bukhari 5075, 5117-18, Sahih Muslim 1404a, 1404c, 1405a-b, and Sunan Ibn Majah 1962.
Later, he 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 sources are unanimous in stating that the perverted, wicked practice of prostitution was allowed by Muhammad for a time, amongst his followers.
And, what does the verse in the Quran call this prostitution? A "good thing". Well, if it was a "good thing", why'd you ban it? And why don't Muslims embrace the fact that they belong to a religion that called prostitution a "good thing", immortalized forever in their fake scripture?
In his teachings, Muhammad did not leave a single part of marriage uncorrupted. What he taught about marriage is entirely contradictory to everything taught on the topic in Scripture.
Because marriage is such a fundamental part of life and society, the amount of misery, perversion, and pain that has been caused by these wicked false teachings is incalculable.