Islam as the perfect religion for all times and all places, is both rational and practical. The wisdom behind the Prophet (SAW)'s plural marriages is to show all possible types of marriage in Islam.
In line with polygamy, most enemies of Islam center their biased criticism on the Prophet's S.A.W plural marriages, which exceeded more than four as allowed in the Quran.
The enemies of Islam branded the Prophet (SAW) as a "sexually obsessed man" (Astaghfirrullah) for marrying more than four. The Muslims have to correct such distorted notions about the Prophet (SAW).
We, as Muslims, should make it clear to the non-Muslims that Allah (SWT) commands us to follow the Prophet (SAW) as he is the best example to all mankind. Allah (SWT) says,
"Indeed in the Messenger of Allah [Muhammad (SAW)] you have a good example to follow for him who hopes in (the Meeting with) Allah and the Last Day and remembers Allah much." (Al-Ahzab 33:21)
The Prophet's (SAW) plural marriages are an example for us to follow. Each marriage set the path to all possible types of marriages in Islam. If he (SAW) was a "sexually obsessed man" (Astaghfirrullah) he would have married more in his early manhood, not after he had passed the age of fifty.
The fact that he married Khadijah binti Khuwailid (RA) and lived a monogamous life (for twenty-seven years) till she died, showed that he (SAW) was not a "sexually obsessed man."
On the contrary, the Prophet's (SAW) marriage to Khadijah (RA) shows only limited types of marriage that are allowed in Islam. His marriage to Khadijah (RA) showed that it is permissible for a man to marry a woman who is older than him, for a poor and orphan man to marry a wealthy woman, for an employee to marry his employer, and for a bachelor to marry a widow.
If Allah (SWT) did not allow the Prophet (SAW) to marry other women, how could marriage in Islam be open to all other types of marriages? Had the Prophet (SAW) not married other women, Muslims who follow the Quran and the authentic Sunnah would find it difficult to enter into marriage with the limited examples from the Prophet's (SAW) marriage to Khadijah (RA).
The Prophet's (SAW) plural marriages after his monogamous marriage with Khadijah (RA), for so many years, show that in Islam it is allowed for a man to marry a virgin woman, who is very much younger than him, as in the case of Aisha binti Abu Bakr (RA). A man can choose to marry a young and intelligent woman like Aisha (RA). He can marry his friend's daughters, in the same way as the Prophet (SAW) married Aisha and Hafsah (RU), the daughters of his closest friends: Abu Bakr and Umar (RU) in order to foster ties of relationships.
A man can marry his enemie's daughters as the Prophet (SAW) married: Juwairiyah bint Al-Harith (RA), the daughter of Al -Harith, the head of Bani Al-Mustaliq of Khuza'ah and Umm Habiba or Ramlah (RA), the daughter of Abu Sufyan (RA). Note that both Al-Harith and Abu Sufyan (RA) were bitter enemies of Islam.
The Prophet's (SAW) marriages to their daughters show how Islam goes for peace and reconciliation. Knowing that Juwairiah and Ramlah (RU) are both from ruling families, man's marriage to women of high social status is therefore, allowed.
Likewise, it is allowed for a man to marry woman of low social class as in the case of Maria (RA), who was given to the Prophet (SAW) as a present by the ruler of Egypt. Ther Prophet (SAW) elevated her status by marrying her, instead of making her his slave.
His marriages to his captives: Juwairiyah bint Al-Harith and Safiyyah bint Huyay bin Akhtab (RU), not only show how Islam tolerates mixed marriages based on social status, but also shows the high regard given to women. Instead of making them slaves, being his captives, he married them and gave them the highest status of women being among the "Mothers of the Believers."
It further shows how the Prophet (SAW) freed women from the bondage of slavery. Aside from inter social-cultural marriages, the Prophet (SAW) also demonstrated that Islam permits inter religious marriage with the People of the Book by marrying Safiyyah bin Huyay bint Akhtab (RA), a Jew and Maria (RA), a Christian from Egypt. Both of them embraced Islam and became among the "Mothers of the Believers."
With the Prophet's (SAW) marriage to Sawda bint Zam'a (RA), a widower can opt to marry a middle-aged, kind, jolly, and widowed woman like Sawda (RA) who can take care of his children.
The Prophet's (SAW) marriages to Hafsah bint Umar bin Al-Khattab (RA), Zainab bint Khuzaimah (RA) and Umm Salamah Hind bint Abi Omaiyah (RA), all widows, show that men should show sympathy and care for widows by marrying them. Had he not married Umm Salamah (RA), a widow with many children, he would not have demonstrated his virtuous teachings on the care of the orphans. He showed kindness to them, treated them just like his real children.
The Prophet's (SAW) marriage to his cousin, Zainab bint Jahsh (RA), who was divorced by his adopted son, Zaid (RA), shows that in Islam, it is lawful for man to marry his first degree cousin. It is also lawful for a man to marry a woman, divorced by his adopted son.
In addition, Islam allows the practice of betrothal before entering into marriage as the Prophet (SAW) did prior to his marriage to Aisha (RA).
It also permits marriage in absentee as in the case of his marriage to Umm Habiba or Ramlah (RA), the daughter of Abu Sufyan (RA), who was in Abyssinia. The Prophet (SAW) asked the King of Negus for Umm Habibah's (RA) hand for marriage, which the King granted.
Non-Muslims should know that Allah (SWT) permitted all of the Prophet's (SAW) plural marriages. The plural marriages of the Prophet (SAW) are a guidance of the believers. They serve as guides on the do's and dont's of marriages in Islam. All the types of marriages that we derive from the Prophet's (SAW) plural marriages are based on the following words of Allah (SWT),
"...(Lawful to you in marriage) are chaste women from those who were given the Scripture (Jews and Christians) before your time, when you have given their due Mahr (bridal-money given by the husband to his wife at the time of marriage), desiring chastity (i.e. taking them in legal wedlock) not committing illegal sexual intercourse, nor taking them as girlfriends..." (Al-Ma'idah 5:5)
"And (remember) when you said to him [Zaid Ibn Harithah (RA) - the freed-slave of the Prophet (SAW)] on whom Allah has bestowed Grace (by guiding him to Islam) and you [O Muhammad (SAW) too] have done favor (by manumitting him) "Keep your wife to yourself, and fear Allah."
But you did hide in yourself (i.e. what Allah has already made known to you that He will give her to you in marriage) that which Allah will make manifest, you did fear the people (i.e. Muhammad (SAW) married the divorced wife of his manumitted slave) whereas Allah had a better right that you should fear Him.
So when Zaid had accomplished his desire from her (i.e. divorced her), We gave her to you in marriage, so that (in future) there may be no difficulty to the believers in respect of (the marriage of) the wives of their adopted sons when the latter have no desire to keep them (i.e. they have divorced them). And Allah's Command must be filled." (Al-Ahzab 33:37)
"O Prophet [Muhammad (SAW)]! Verily, We have made lawful to you your wives, to whom you have paid their Mahr (bridal-money given by the husband to his wife at the time of marriage), and those (captives or slaves) whom your right hand possesses - whom Allah has given to you, and the daughters of 'Amm (paternal uncles) and the daughters of your 'Ammah (paternal aunts) and the daughters of your Khal (maternal uncles) and the daughters of your Khalah (maternal aunts) who migrated (from Makkah) with you, and a believing woman if she offers herself to the Prophet, and the Prophet wishes to marry her; - a privilege for you only, not for the (rest of) the believers. Indeed We know what We have enjoined upon them about their wives and those (captives or slaves) whom their right hands possess, - in order that there should be no difficulty on you. And Allah is Ever Oft-Forgiving, Most Merciful." (Al-Ahzab 33:50)
All of the types of marriages as demonstrated by the Prophet (SAW) show that Islam is indeed, complete, rational, and practical for all times and all places. In short, Islam is the perfect religion for all mankind! Allahu Akbar!