How do we respond to Christian missionaries' accusation that Islam permits slavery and violates human freedom and rights?

Slavery in Islam differs completely from that in Judaism, Christianity, and contemporary civilization. Islam affirms that Allah created man with full responsibility, and that no one has the right to restrict his will except justly. Slavery in Islam is permissible, but a fair perspective requires examining its subtleties. Islam came when slavery was widespread for various reasons, such as wars and poverty. Islam forbade the enslavement of a free person through a divine hadith (Hadith Qudsi): (Three are My adversaries on the Day of Resurrection... a man who sells a free person and consumes his price).

There is no text in the Quran or Sunnah that commands enslavement, while there are dozens of texts that call for manumission and liberation. Islam restricted the sources of slavery to prisoners of war from among the disbelievers, their women, and their children. If a disbeliever is captured, the Imam has the option of granting them grace, ransoming them, or enslaving them. The conversion of a slave to Islam does not invalidate their ownership; rather, it is encouraged for the owner to free them.

Islam did not abolish slavery entirely because the disbelieving captive was an oppressor or an accomplice to oppression, but it placed restrictions on a person who exploited their freedom in the worst possible way. Islam imposed multiple means for freeing slaves, including zakat and expiations for sins, and encouraged their emancipation. Islam also guaranteed slaves rights in treatment, including food, clothing, preservation of dignity, justice, and kindness, and permitted a slave to purchase his freedom through manumission contracts (mukataba).

In contrast, Judaism and Christianity widely sanctioned slavery. Judaism permitted the enslavement of Hebrews and others, and Christianity neither prohibited nor condemned slavery. Contemporary Europe also practiced slavery in brutal ways, causing great suffering to Africans, and built its civilization on the enslavement of millions. Its conscience did not awaken until the last century with the issuance of the protocol for the prevention of slavery.