"Slavery is free, so how does it support it?"
What the f*** are you even talking about? The religion allows slavery for those born slaves and non-Muslims, how much clearer can one make that?
It is still their holy book, and considered the final word and total truth from Allah.
"With over 150,000 slaves, Mauritania ranks first globally as the country with the largest slave population. In other hot spots of the MENA region, Sudan, Libya, Saudi Arabia, Jordan and the UAE were scarlet lettered out as the countries that had the ignominious honor of hosting the most number of slaves."
Slavery is STILL a problem in Islamic countries. They still consider the Quran which allows slavery their holy text and the absolute truth, do you not see an issue? Do you not see a problem that slavery is a problem TODAY in Islamic nations?