If Islam is supposedly against slavery, and by its rules slavery should gradually disappear, why is it that slavery still existed at the time of the later Imams?
Islam came to a world full of slavery as part and parcel of the whole social and economical systems which was practiced for thousand of years. Islam started the procedure to gradually melt slavery system. The result of the Islamic anti slavery rules, slavery decreased among Muslims till it became very rare among Muslim communities till today while slavery was practiced in Europe and Americas one thousand years after that and till the 19 th century.
'Islamic rules were the best practical rules which dealt with the slavery and diminish it if few centuries.
Wassalam.