Where are the churches on the Enterprise??? Next to the bathrooms I guess?
There is clearly religion in the future. Spock even mentioned God, the Bajorans believe
in the Prophets. Hell, even that Dumbass Sybok believed in God, and he found.... well,
not God, but if there's a Devil...
Bringing up Star Trek V...yeah not the best idea in most discussions. I remember reading Nimoy's book (The "I Am Spock" one, not the other) where he talks about trying to talk everyone out of using that script and that mixing Star Trek and religion that closely was a bad idea. To paraphrase how he put it (since I don't remember the exact quote), "if we find God at the end, the audience will never buy it. If we don't find God, there's no story."
But yeah, there's religion all over Star Trek in bits and pieces. Sometimes its a just a detail for the characters, sometimes it becomes a big part of the plot or theme, like the episode where Picard was mistaken for the god of a planet.