Many of them have beliefs that are explicitly against their religion, like ghosts and past lives.

Baptists in particular are obsessed with hell, demons, spirit possessions, and sin. Any sins committed by a Baptist is never their fault because it was the devil controlling their actions (but people they don't like are inherently sinful). Pentacostals are obsessed with the end times of black horses riding in the night to take them away once Jesus comes and eliminates most of humanity in a titanitc war that they pray for daily.

America is the Saudi Arabia of the Christian world and that version of Christianity is dissimilar to Christianity anywhere else in the world.

The "mainstream Protestantism" has been fused with capitalism where wealth = godliness in the form of prosperity gospel. Catholics are just about the only normal Christians left, along with Lutherans and the like, and they have quite a bit of their own issues.