It was once said that there are no atheists in foxholes and I suspect the same might be said of being a spacefaring race. Though Aliens & Asteroids may be set a couple of centuries in the future, I suspect that our need to call on a higher power in a time of need may still be very relevant, if not more than it is today.
But let me caution you. I’m not saying that everyone will be carrying a holy book and praying on Sundays. I suspect that we will go back to more private religious observations and practices. And space is plenty big enough for atheists too, but confronting the human condition in the harsh vacuum of space is likely to provide a huge attitude change for many of us moving forward.
Humanity will bring all the “good books” into space, though some practices may have to change due to geographical constraints. (That said, knowing where Earth is located while far away and pointing that direction while in prayer is probably not an impossible task.) Uttering a small prayer before donning an environment suit or performing a potentially dangerous task is completely understandable. After all, deities are not constrained by time and space as we are as physical beings.
One of the things early astronauts noticed when they were in space was how it gave them a cosmic perspective on things. Political squabbles about lines on a map don’t mean as much when you’re watching Earthrise from our Moon. And though I would like to think that we as a species could learn from that perspective, I don’t think we can combat human nature in such a short amount of time.
However, regardless of any individual religious practices any individuals may adhere to while on a ship floating in the void, I think there will always be a place for the clergy in human civilization. And in some of the larger settlements, such as the Lunar or Martian colonies, I think we will find churches representing all the major faiths just like we do on Earth. Religious freedom should still be a thing in the future, so long as it doesn’t conflict (too much) with the corporate ideals espoused by the member companies of the Dominion.
Confronting the void will be a very personal journey, but religion will still be there to provide a moral and ethical framework by which an individual can find their place in society. Keeping a sense of connection when floating in the vacuum of space connected by a lifeline will be paramount to not simply losing your mind.
And there will be plenty of room for religions other than the major ones of today to gain a following. For instance, the followers of the Norse Gods today would feel right at home in space — and other strange or historically-based religions will be right there alongside them. Why not have a religion based on the worship of the Old Ones from the Cthuhu mythos invented by Howard Lovecraft?
So I fully expect there to be individuals embedded in Space Marine groups who follow religious practices. And I expect there to be churches on settled worlds, in space stations, and anywhere people gather.
Lastly, there’s plenty of real estate in the universe once we leave Earth. The establishment of settlements on remote worlds dedicated to religious ideals such as monasteries will be inevitable. And members of those religious organizations leaving “home” to spread the word? Definitely.
We’re human. You can bet that we’ll be bringing our religions with us and spreading them across the stars!