slavery in europe was never under the jurisdiction of and explicitly condoned by the religious authority, and it never played a role in the social structure of europe, they had a fuedal system for a millennia which is an entirely different thing. The history of slavery with respect to europe is just merchant companies buying slaves and working them on foreign cash crops. This is very different than having six of the largest slaves trades in history localised all within mediterranean islamic states who's conduct was explicitly endorsed by islamic law and was inherent to the social structure of those states (i.e. algiers, tunis, cordoba, ottoman empire and mamluks especially). Theres more nuance to the topic than just the presence of slaves somewhere at some point in time in a given region. It's a part of that difference between how the systems of slavery were integrated with the broader structure and legal system, with europeans as I said they barely existed IN europe, and were completely unregulated by the civil and religious authorities, whereas in islamic states you had servant slaves, sex slaves (many of which were children inshallah), labour slaves, slave soldiers, virtually every sector of society involved slavery and it was all regulated under a framework of islamic law. It's a challenge to find a modern sheikh or 'scholar' that would actually condemn slavery of non-muslims for this reason, islam is a slave culture, and much like with their prophet being a pedophile, they tend to double-down rather than reform