I havnt looked into paganism in a long time but i think their used to be some small amount of human sacrifice, not on a massive cruel scale like the Aztecs'. I think it would make sense for Christianity to come around there, and when the Pagans ask about the sacrifices Christians say "Sacrifices? Oh no dont worry about that, Jesus was so perfect we dont need to do sacrifices anymore. He taught us to pray within our minds or out loud if we need forgiven of sins because He is always listening and loves us very much." Which would probably blow their minds. I'm sure alot of cultures eagerly swapped to Christianity when they offered an alternative to sacrifices.