The Bible supports slavery !

If the Bible so obviously condemns slavery then why did the the Catholic Church not explicitly say so until modern times? For instance only in 1866 The Holy Office of Pope Pius IX affirmed that, subject to conditions, it was not against divine law for a slave to be sold, bought or exchanged. The best it could do until very late on was to issue papal bulls condemning "unjust" enslavement ("just" enslavement was still accepted as a form of punishment), and mistreatment of Native Americans by Spanish and Portuguese colonials; however, these were largely ignored. This while Protestant missionaries in the early modern Atlantic World developed a new vision for slavery that integrated Christianity with human bondage. Protestant slave owners fiercely guarded their Christian rituals from non-white outsiders and rebuffed the efforts of Quaker, Anglican, and Moravian missionaries to convert the enslaved population. For planters, Protestantism was a sign of mastery and freedom, and most believed that slaves should not be eligible for conversion. And so on. This is not to say that there were not early Christians working against the odious institution and helped to seed its downfall of course, but any moral lead has often been half hearted and mixed, arguably reflecting the equivocating stance of scripture.