You gotta have faith

[Matt W]

Religion - in some form - would survive into the post-apocalypse.

The form of religion will be dependent on the community. A group of Wanderers will develop some useful taboos, for instance (mostly about food hygiene and interaction with outsiders).

The name "Christianity" will survive. However, the religion may take some bizarre forms. Cynics will point out that it has always done so. If Hutterites and Creflo Dollar can both claim to be Christians, then the term is very "elastic"

I don't think that there will be many Cargo Cults. Those came about because of encounters with totally alien cultures. BUT there might be something like ancestor-worship. The "Founding Fathers" regarded as saints, maybe?