Religion has had long periods of being fairly static same as other parts of society.

Determine how much technology and society changed and work backwards from there.

What I like to recommend to people is to not try and be overly fancy for its own sake and instead work with the concerns that would affect your period and people.

Enlightenment and salvation religions largely took over in our world because technology and organization started to make how people conducted themselves towards each other more important than daily entreaties towards the forces governing minutea of survival. Atheism (as well as very moderate religiosity) in turn derives from our ability to provide safety, adjudication and prosperity in an incredibly consistent manner so people don't ascribe their existences to higher forces.

In space a lot of this falls away.

-The air you breathe is dependent on machines

-You're inside a thin bubble separating you and immediate death

-Every single aspect of living has to be sustained and maintained through active effort

-Jurisdiction is always shifting

-Even in an ultra FTL universe there's going to be blank spots on the map of enforcement and adjudication

Etc.

This would be a good place to start.