Not only did they homogenize but they also became bastardized version of their specific branches while they were at it, with maybe the exception of the Mormons but they’ve always been shit. Historically a lot of these Christian sects were more than capable of handling non belief since they would just leverage culture and economics to maintain relevance, think like how John Brown while a complete zealot was more than willing to work with folks who he considered quite questionable since all are sinners but also kill all slavers. While this could be abusive there were also plenty of situations where the individual priests were closer to community leaders than anything else, hell one of my ancestors went to church where they had a Scottish protestant, a Irish Catholic, and Swiss Jew as the priests they only tried to stab each other over politics.

But well as a lot of things go they sold their souls to the devil, which is to say they traded long term influence and stability for short term relevance and political power. They’ll burn out eventually since even in the Bible belt folks are getting sick of that shit, frankly it’s more a question of how much they’ll break before they’re too weak and irrelevant to do any more damage.