Secular Hero

""He did not often feel the need for a physical expression of his religious feeling. Like Brion [his deceased brother and the last king], he preferred to witness for his faith through the example of an upright life, rather than spend overmuch time on his knees, in a building that took the place of belief for many folk.""

- The King's Justice by Katherine Kurtz

Picture an author at work, creating a hero. The notes and the drafts cover many traits: height and weight, the colour of his hair and eyes, what clothes he wears, where he lives, where he went to school, what family he has, even his favourite food and the playlist on his mp3 player. References to all these things and more are worked into the story, but one topic doesn't come up much: his religion. Not that he necessarily doesn't have one (he might or he might not); he just doesn't talk about it, and the world in which he moves, while it has one or more thriving religions, doesn't make a big deal of it either. Why is that?

Obviously, most authors want to appeal to as large an audience as possible, and one way to do that is to reflect the audience and their world in the work. Depicting a lot of church services that aren't plot relevant may bore the audience, taking a particular religious stand may turn some people off, and most people are neither holy rollers nor antagonistic atheists. Conversely, some authors write for a niche market of conversion stories, and starting the target of the conversion in this middle-of-the-road place is both more likely (a devout member of one faith is less likely to change to another) and more common statistically speaking.

The Law of Conservation of Detail can be a factor. If a given plot doesn't require a character to be in a church service, the audience won't see him in one. Over time, this can lead to the audience assuming this character doesn't have a religion or doesn't practice it much. Other aspects of a story may simply preclude religious participation, such as a character working in a demanding job or on an unusual schedule. More obvious examples show these characters interacting with religious figures (usually due to plot demands) so that the topic of religious practice (and his lack thereof) comes to the fore. In these instances, the character will express his religious apathy overtly or have it described or both.

Many other reasons for downplaying religion involve characterization. Perhaps our hero prefers to live his creed rather than profess it much; for this guy, his deeds are his devotions, and "God helps those who help themselves." Then again, perhaps he's compartmentalized his life; he goes to church once a week and the rest of the time he's getting on with the business of living. (These cases have some overlap with the Nay Theist.) Maybe he's a believer who's uncomfortable with asking for divine help or bothered by the idea that Somebody Up There might be taking an interest in him (If God Is Evil or a jerkass, can you blame him?).

Note that the in-universe society might have a common religion that everyone presumably follows (such as medieval settings or other places with a dominant religion), or it may have many religions with no one sect that's predominant (the USA being a major example). Also note that this hero may not believe in a deity at all and finds it a waste of time to dispute the matter with others. The hero's secular nature may only become clear if/when religious topics are addressed. For whatever reason, this guy has better things to do.

This trope is neither Hollywood Atheist nor the Flat Earth Atheist, who holds back belief despite evidence to the contrary. In works with Physical God(s), a character who acknowledges but does not worship them is a Nay Theist.

Anime and Manga

 * Much of the SSS in Angel Beats!, but especially Yuri Nakamura.
 * Edward Elric from Fullmetal Alchemist claims not to be interested in religion, even though he's met God.
 * Sonozaki Shion of Higurashi no Naku Koro ni is sent to a Catholic school (against her will) and escapes, later on saying "If I stayed in a place like that, I'd either end up brainwashed or insane!" She also denies the existence of the village god, Oyashiro-sama on a lighter note.

Literature

 * Ciaphas Cain kinda lives in a setting where God-Emperor of Mankind is very observable, but he thinks he's too busy fighting the countless forces of Warp to care about him personally (though never misses jokes at Cain's expense)
 * With the notable exception of Brutha from Small Gods, none of the Point of View characters in the Discworld pay much attention to any of the Disc's many gods (The Last Hero notwithstanding). And Brutha is more spiritual than religious, despite caring for an avatar of his god.
 * Despite the medieval setting and the presence of many clerical characters, some characters in the Deryni works are less than devout.
 * Nigel Haldane: The opening quotation describes him preparing to have his nephew King Kelson trigger some of the family's arcane powers in him. Given that he's facing an unfamiliar arcane ritual that also makes him confront the unwelcome possibility that he may become king himself, he feels the need to pray: "A little awkwardly, then, he bowed his head and framed his thoughts in a far more formal petition than was usually his wont..."
 * Alaric Morgan fits as well, partly in contrast to his more devout cousin Duncan McLain. Morgan once used his magic to contact his aide-de-camp during a religious service, and used fasting as a cover/excuse when he fainted from the effort. The morning after the knightly accolades of Kelson, Conall, and Dhugal, Morgan arrives late to an Ash Wednesday Mass, having stayed up to celebrate with Nigel and an excellent port the night before. He is elsewhere described as being uncomfortable with the idea of receiving the attention of Heaven. He does ask his cousin to give him a blessing (after said cousin became a bishop), and Duncan expresses some surprise at this request; it happens on the day Duncan (who is like a brother to Morgan) was leaving on a military campaign, with the unspoken possibility they night not see each other again.
 * Detective Meyer Landsman of The Yiddish Policemen's Union is obviously culturally and ethnically Jewish, religiously agnostic. Landsman's personal issues, including his (lack of) religious identity, are a major subplot.
 * Father Robert Koesler, of William X Kienzle's murder mystery series, lives a life largely of quiet faith, laughing at the more ridiculous rituals of the church and bending the rules where he feels it leads to a more harmonious conclusion.
 * The Dresden Files: Harry Dresden is not religious, despite working for archangels, being friends with holy knights on payroll from God Himself, and seeing how incredibly powerful faith can be. He is a direct inversion of the most common application of this trope - instead of being too heroic for silly little churches to bear his awesomeness and insight, he adores religion, but thinks he's not a good enough person to be associated with it.

Live-Action TV

 * Bill Adama from Battlestar Galactica did not believe in the Gods. This led him into conflict with President Roslin on several occasions. Adama's theological view evolved in the course of the series from atheist to non-religious believer.
 * Jeff, the main character of Community, is agnostic and opts for not talking about religion to keep the peace in the study group, whereas all other characters have relatively strong religious or atheistic beliefs: "To me, religion is like Paul Rudd. I see the appeal and I would never take it away from anyone, but I would also never stand in line for it."
 * Firefly: Shepherd Book is a Christian preacher, and Inara is apparently Buddhist. The other characters don't have a problem with an open display of religion, but Mal most definitely does. "You're welcome on my ship...God ain't." He's not an atheist or at least he didn't used to be (in a blink and you'll miss it moment during the Battle of Serenity Valley in the pilot, he's shown kissing a cross he's wearing around his neck); since the War of Independence he's just become either agnostic or angry at God (or both).

Web Comics
"Bureaucratic Deva: Let me ask you something why did you never consider becoming a cleric yourself? You have halfway decent Wisdom and Charisma scores, you could have pulled it off. Roy Well is awkward to say, given where I am, but I've never been that religious. Roy: I mean. I guess my mom raised me to worship the Northern Gods, but I always figured as long as I don't actively offend any of them, they'd leave me alone."
 * Roy from The Order of the Stick: