The problem arises when religious teachings are used to justify evil.
For example, religion can be used to justify enslavement of womenfolk of enemies defeated in Jihad, rape of those enslaved women, and selling those enslaved women in the slave market.
See this Hadith (Sahih Bukhari Volume 3, Book 34, Number 432)
Better not to take things out of context.
When Islam was reveled to Prophet Muhammad (peace and blessings be upon him), slavery was a worldwide common social phenomenon; it was much older than Islam. Slavery was deeply rooted in every society to the extent that it was impossible to imagine a civilized society without slaves.
In spite of this social fact, Islam was the first religion to recognize slavery as a social illness that needed to be addressed. Since slavery was deeply rooted in the society, Islam did not abolish it at once. Rather, Islam treated slavery in the same manner it treated other social illnesses. Islam followed the same methodology of gradual elimination in dealing with this social disease as it did with other social illnesses, for example: the prohibition of alcohol in three steps.
It was a war custom in the past to take men and women as captives and then turn them into slaves. Islam did not initiate it; rather, it was something in practice long ago before the advent of Islam. And when Islam came, it tried to eradicate this practice, bit by bit. So it first restricted it to the reciprocal practice of war, in the sense that Muslims took war captives just as the enemies did with Muslims.
But as it aimed at putting an end to such issue, Islam laid down rules which would eventually lead to eradicating the practice. So it allowed Muslims to have intercourse with slave women taken as captives of just and legitimate wars. In so doing, the woman would automatically become free if she got pregnant. What's more, her child would also become free.
Not only that, Islam also ordered a Muslim to treat the slave woman in every respect as if she were his wife. She should be well fed, clothed and given due protection. In the family environment, she had the opportunity to learn about Islam and was free to accept it or reject it. She also had the opportunity to earn her freedom for she could be ransomed.
Some people misunderstand the wisdom behind the permissibility of having female slaves and think that it is meant to unleash mens desires and give them more enjoyment. Never! That is not the point! It is, rather, means of freeing slaves; and this is clarified above in the fact that if a master got a female slave pregnant, then he could neither sell her nor give her away as a present. And if he died, she would not be considered part of his property. She'd receive her freedom and her baby would also be free.
As for marrying slaves, it was something permissible under two conditions: first, if one was unable to pay the dowry of a free woman. Second, if there were fear of committing adultery if one doesnt get married. This is clarified by the following verse:
And whose is not able to afford to marry free, believing women, let them marry from the believing maids whom your right hands possess. This is for him among you who feareth to commit sin. But to have patience would be better for you. (An-Nisaa: 25)
This verse shows that Muslim men should abstain from illicit relations and seek enjoyment through marriage to free women or through their female slaves.
Thus major hindrances in the complete abolition and prohibition of the institute of slavery were:
1. The existing internationally accepted social status given to the slaves and their prevalent moral training and position;
2. The social acceptability of interacting with slaves;
3. The macro economic situation in the societies (including the lack of employment opportunities for the unproductive slave population);
4. The serious socio-moral and political implications that were likely to follow a hasty action in this regard; and
5. The international situation
The basic directives of Islam in this regard were aimed at:
1. Promoting freeing of capable slaves through various directives;
2. Improving the social status and the moral standards of the slaves;
3. Abolishing any future chances of converting any free men into slaves; and finally
4. Awarding the legal right to each and every capable slave, who wanted to live his/her life as a free person, to earn his freedom.
These directives amounted to the best possible solution to the problem with the least potential of any negative repercussions on the society as well as the individuals. During this process, it was necessary not only to better the social status of the slaves in the society but also to recognize the relationship between the slaves and their masters.
The first woman in the history was daughter of Hatim Tai Sufana, who was taken as a prisoner but was released by the Prophet Muhammad(peace be upon him) . Hatimtai formally Hatem ibn Abdellah ibn Sa'ad at-Ta'i was a famous pre-Islamic Arabian poet,. He was a Christian, and belonged to the Ta'i Arabian tribe. Stories about his extreme generosity have made him an icon to Arabs up till the present day.
So my dear sir, one thing picked out of context, can be very devastating.