It was the Catholic Church that established the dogma that slow ate away the FOUNDATION of social acceptance of slavery.
The Catholic Church and NOTHING ELSE is responsible for that early work that all later anti-slavery work was based on.
For centuries it was ONLY Catholic dogma that kept witch hunting SURPRESSED (Charlamagne personally promised to hang anyone who used 'witchcraft' charges to justify a crime, and he was only one voice over a period centuries.....). Sadly, the church was not able to root out the superstitious beliefs, and was eventually contaminated by them. It is astonding it took so long.
The roots of the science we use all trace to, or through, Church SUPPORT. The church haters love to cite examples of surpression, but even then, most of those are misrepresented (Galileo had his problem more from HOW he said what said, than WHAT he said. Others were brushing the same ground, but with more manners. In an age of kings, being brillant does not grant immunity for insulting the establishment, especially when others are saying the same sort of stuff WITHOUT being insulting....)
The Church's problems came from getting to tied up in BEING a state. Even the Church knew this was causing problems (See Celestine V). Sadly, as Celestine V proved, once you ARE a great power STATE, you can't go back to being just a Church just by electing a spiritual Pope. You are stuck with Prince/Popes until you are no longer a major State.
Try, for just a moment, to entertain the idea that many people from all walks of life in the past were NOT cynical sexually twisted monsters, and were actually in many cases simply admirable people.