Belief in God implies some effect on one's behavior, unless you believe in a completely impersonal Prime Mover that retires thereafter.
The notion that one is a Boltzmann brain doesn't really change anything. If you are, there's absolutely nothing you can do about it. So the only sensible thing is to assume that you aren't, regardless of probabilities.
I've seen a paper (probably by Bostrom) deducing normative statements ("oughts") from the simulation hypothesis (purely descriptive, "is"). Namely: the grad students running these simulations are more likely to switch off boring simulations. Thus, if we want to keep living in this world, we should strive to make it interesting.
I must say, with Trump, Brexit, war, and more Trump: Well done, folks!
Our world is boring though, cf Boötes Void. Those transcendental extrauniversal aliens invented quantum physics, what do you expect them to believe? If their world can create such immense simulations, maybe it's because their world is too fabulous and they look for serenity.
