I wish there was more of a legit "space religion" mechanic in this game. The next expansion is supposed to be based around the shroud from the title of it, so maybe we'll get some kind of spiritualist update as well?

As it stands, spiritualists are mostly one religion that loves psionics and the shroud and hates robots. There's not much room for robot religions or machine cults. There's also not much room for thinking that the Shroud isn't Heaven, but Hell, and that psychics are witches and shroud entities are demons. There isn't really much of a mechanic around converting the unbelievers. All spiritualist pops are basically regarded as part of your "religion" no matter what it is, and even the corporate prosperity gospel thing regards spiritualist pops as already part of its religion. Your various religious tenets all seem to be taken from the spiritualist fallen empires too. Like you can consecrate holy worlds which shouldn't be inhabited... for some reason. The spiritualist fallen empire does it, so you do too because you're a spiritualist, and there's no given reason why the spiritualists even believe in holy worlds and think holy worlds shouldn't be inhabited.