In case you missed it, yesterday was the 50th anniversary of the single most influential television series in history: Star Trek.
Star Trek is often seen in a kind of post-religion universe, but that is only if you are not paying attention.
(Most of the research that follows is not original to me, I have just collated it from various websites.)
The Original Series
In "Balance of Terror" the Enterprise is shown to have a chapel with multiple religion symbols. In "Bread and Circuses" we have the strange parallel Earth where there are "sun" worshippers who turn out to be "Son" of God worshipers - at least according to Ahura. Kirk seems to be a monotheist in "Who Mourns for Adonis" when he says "Scotty doesn't believe in gods" and also "Man has no need for gods. We find the one quite sufficient." Once you get to the movie era the quest for spiritual understanding in Star Trek comes to the fore, but we do not talk about the odd numbered movies.
The Next Generation
In TNG it is really Worf and Data that are spiritual seekers. Worf in a very overt way both in this series and DS9. While Klingon religion is closer to Confucian teachings with a heavy dose of Bushido, it has a messiah. Worf visits a monastery, in "Rightful Heir", where he has a vision of the Klingon Messiah Kahless, who later appears -all be it as a clone programmed by the religious order to take over the Empire. Data, the android who wants to be a real boy, is the archetypal spiritual seeker from the first episode onward. There we see him practicing whistling - think of it as a novitiate's prayer, and progresses through seeking emotions, his father, his family, having dreams, having emotions, and ultimately self sacrifice and possible resurrection.
It is worth noting that there is a "god" figure in TNG in the form of Q, who is a constant thorn in the Captain's side. Q, however, is the argument against worshipping beings who just happen to be more powerful than you.
The series that took religion the most seriously, to the point of making it at least a back ground element of every episode (Bajoran ear rings if nothing else). It is ultimately the story of a messiah, the "Emissary" Benjamin Sisko whom we ultimately learn is half-human and half-divine (or half-wormhole-alien-worshiped-as-a-god if you want to be materialistic about it.) His father's name is even Joseph! Q shows up and is seen as a powerful alien, but the Prophets (the wormhole aliens) are never so clearly defined by the series.
Voyager had its own messianic prophecies later on in the series, with B'elanna Tores and Tom Paris' 1/4 Klingon child who is supposed to be a sect of Klingon's kuvah'magh. It is Chakotay who shows the most constant religious faith through the series. He practices rituals like meditation with an animal guide (VOY: "The Cloud"). We learn that his tribe may have had contact with aliens in the past (VOY: "Tattoo"). Directed dreaming enables him to trick aliens that want to take over the ship (VOY: "Waking Moments"). While he admits there may be no afterlife, but such a belief is not necessary to religious belief and practice.
Enterprise is not so far removed from our time and neither is it so immersed in the Utopian future seen in TOS and TNG. Human religious elements show up periodically, but the most constant theme is the struggle of the Vulcan's with their own faith. Even though they would not call it a religion, the teachings of Logic set by Surak certainly would qualify as such. Even the techniques of meditation and the latent psychic powers of the Vulcans have a religious air to them.
In many ways Star Trek is the quest for enlightenment. It is full of false steps and possible short cuts. But it is also the idea that there is always more. A better understanding. A bigger purpose than we can see. That, inherently, is what religion is - whether anyone intended for the show to be that or not.