According to academia, apologetics comes from the Greek apology, which means to launch a defense. Some Muslims are defending the practice of concubinage, not for our present times, and they describe it in an ideal way. It's not only Muslims that launch an apologetic for the concubinage in the past. However, this is an issue for many Christians as well.
One can find many YouTube videos in which Christians are trying to explain why concubinage was practiced by some of the biblical patriarchs. For Christians, it's a lesser problem, because in the New Testament, there was no representation of Jesus being married to begin with, and there is no mention that he ever had a concubine. Whether he was married, is still an open question for some scholars. For example, Anthony Ladon wrote a book entitled "The Wife of Jesus" with a question mark. He thinks that it's possible that Jesus may have been married, but no mention is ever made of Jesus having slaves or having a concubine. It looks like he did not have much property because he's reported as saying, "The son of man has nowhere to lay his head."
Yet, in the New Testament, slavery is still a reality, and some people may have owned slaves, not may have, but owned slaves. Paul says, “It doesn't matter whether you're a slave or free, and if you're a slave, don't try to become free, and if you are free, don't try to become a slave, and he cautions the runaway slave to return to his master.” There were slaves, and some of the slaves were naturally female, and among the female slaves, there would have been some who were taken as concubines by their masters.
Why isn't this being condemned in the Bible?
Many rise to the occasion, so there was some apologetic discourse there as well. Much of that discourse says, "This was descriptive, it was what was happening at the time, but was not actually prescribed by the Bible." One might have more to say about that apologetic. However, the Muslim defense described the practice in classical Islamic societies, what is reported to have been practiced by the Prophet Muhammad, Peace be Upon Him, what was more clearly known to be in the practice of the early generations of Muslims, and how they approach this issue. Often, they present a sort of ideal, and they say, "This was not so bad. It wasn't even bad at all." They fail to look at it from the point of view of the hapless young woman who found herself as a slave and as a concubine, and could do nothing about it, she didn't really have a choice to get out of that situation.
Consequently, it’s important to look at that harsher reality. However, some apologists bring forward, and there was a certain ideal unless it is balanced by the realities. They are facts that need to be brought into the whole discourse. People can appreciate and understand what, and why it was done. Last, people realize why we shouldn't be doing that currently.
What was unique in the Islamic understanding of concubines?
This comes under the broader umbrella of slavery. In the Islamic context, it is widely recognized that slavery, as practiced in the earliest Islamic societies, was not like 18th century American slavery. People can be seen in chains, people are being beaten, and the strikes from the whips are cutting their backs. That's a different sort of reality.
In the Islamic context, there is a statement of Prophet Muhammad (PBUH) stating, “If you have a slave, then you are to feed them with food that is similar to what you're eating, clothe them with clothing that is similar to what you wear, you are not to refer to them as your slave, but you can say my boy rather than my slave, because we are all to be slaves of God, and one is not a slave to the other.”
The conception is different for perceiving slaves. We see slaves as our brothers. The main difference is that God has so arranged things that they happen to be under our power, but they're still our brothers in humanity, and sometimes even brother in the faith.
If one was taken as a slave when he happened to be a non-Muslim, especially in war, he's taken as a prisoner of war, but if he converts to the religion of Islam, his master may choose to free him. He became a brother in the faith, or he may remain in that situation. Generally, the status of slaves was improved in Islamic societies vis-a-vis what was seen in other societies. It was thought to be an act of goodwill to free the slave as a charitable deed, even as an act of penance for some sins that we commit. When it came to female slaves, who were taken as concubines by their masters, they might be freed, and then the master may marry her. She's a free person, and she is thought to be now the possessor of the right to give free consent.
While she remained as a concubine, she could not be forced into prostitution. The Quran states:
“Do not force your slave-girls into prostitution, when they themselves wish to remain honourable, in your quest for the short-term gains of this world, although, if they are forced, God will be forgiving and merciful to them.” Quran [24:33].
They would have a concubine being used for the sexual pleasure of the master. In addition, she would be sold or rented out for the monetary gains of the master. However, she could not be sold, and she could not be used as a prostitute.
She was committed to a sexual relationship only with her master. She was not a toy to be used around. If the master chose, he could marry her off to somebody else. However, that would be a permanent relationship of marriage with the other person. She might be in a unique circumstance where she's owned by one person, but she is the wife of another person.
Yet, the person who owned her can no longer have any sexual relationships with her because she is now committed to one person. It’s like a sort of marriage, but without being given the name of marriage. There is a very crucial difference is that the woman, as a slave, did not have the right to consent.
One can mention the ideals, we can count on the good spirits of the Muslims at the time to make sure that she is being married to somebody that she is happy to be married to, so we can bring consent into play. We can imagine and expect that it must have been in the works. From a legal perspective, she did not have that right to consent.
When the practice in Muslim societies was compared with the practice outside of Muslim societies, one can see that there is a great advance in the rights of slaves and concubines in Muslim societies. If the concubine bore a child for her master, then the child would be born free, as opposed to some other contexts in which the child would continue to be regarded as a slave.
Moreover, the woman receives a special status in Muslim society. She's regarded as the mother of the child. In Arabic terminology, it’s called “Umm al-walad,” and she could no longer be sold by the master to somebody else. Consequently, if the master dies before her, then she would be automatically free. The child could inherit from the child’s father because this is a legitimate child to the father.