"In 1938 it was understandable that a pair of young Jewish artists might have wanted to imagine a champion. A Messiah, even. So there is no way that Superman can be Jesus. (His adversary is called Luthor, for goodness sake.)... Mario Puzo's script for the 1978 Superman movie had Marlon Brando drawing fairly explicit parallels between the origin of Superman and the birth of Jesus, even though it is blindingly obvious even in Puzo's own script that the real parallel is with Moses... Spider-Man, Frodo Baggins, Neo, Leo DiCaprio, Indiana Jones – Hollywood turns all its heroes into Christian symbols. (All except Aslan, obviously.)..."
UPDATE 4: Julia Baird agrees:
... Some say he is Jewish, as he was created by two Jewish cartoonists and could be viewed as part of the golem myth - the legend created to protect persecuted Jews in 16th-century Prague. In his early years, Superman often engaged in battles against the Nazis. His birth name was also Kal-El, which is similar to the Hebrew Kol-El, meaning voice of God. The scholarly consensus, though, seems to be that he must be Methodist, largely because Clark Kent was brought up in the American Midwest...
Superman is not the only superhero thought to be religious - Wonderwoman fancied ancient Egyptian religions, Batman is said to be a lapsed Anglican or Catholic (because of the crosses on his parents' tombstones), as is the Hulk. Rogue from the X-Men was raised as a Baptist, and Spider-Man prays to what is assumed to be a Protestant God...
- "A Sunday sermon from Superman", Sydney Morning Herald (22 June 2006)
IT'S KABBALAH-IN' TIME! [updated]... It's official: Ben Grimm, a.k.a "The Thing" in Marvel Comics' Fantastic Four, is Jewish. And devoutly so. Link via James Lileks, who comments: "Reed Richards? Episcopalian, I’d bet. Silver Surfer? Unitarian."
The religious affiliation of fictional super-characters is an intriguing topic. Some are, err, confessedly Catholic (X-Men's Nightcrawler, DareDevil's Matt Murdoch), while others are obviously Baptist or Methodist (Superman's Jonathan and Martha Kent, Spiderman's Aunt May). Other characters, though, are harder to call.
Some years ago, one of Superman's creators (either Jerry Siegel or Joe Schuster, I forget which) mentioned in an interview that they made Kryptonian society crypto [so to speak] Hebraic in many respects, much as Leonard Nimoy did for the Vulcans. For example, Kryptonian male names end in -El, while female names end in -a[h]. Not surprising, since JS and JS were Jewish themselves.
This may explain Jerry Seinfeld's Superman fanhood. Australian radio comedy duo Martin/ Molloy's take on this news: "Superman, Jewish? Must have had a really difficult time trying to circumcise him!" Presumably Kal-El's not Orthodox (his super-hair doesn't grow -- which is fortunate, since nothing on earth can cut it -- therefore no long curls at the temple; and his hat would blow off as he flies!). Any potential marriage between Superman and Lois Lane could well be contrary to the Orthodox Jewish (and Catholic) prohibitions, if one classifies their relationship as "sodomy/ bestiality" rather than "involuntary infertility".
OTOH, as has often been observed (eg, in apostate Anglican Bishop John Robinson's book Honest to God), Superman also has many parallels to Jesus Christ. (Guy with super-powers who looks like an ordinary human arrives on Earth... adopted by kindly couple... grows up, goes off into barren wilderness to communicate with his Father, then realises his mission... etc. RC readers might add, "Main bad guy is named Luth[e]r".) Alan MacDonald noted in his book Movies in Close-up that when Steven Spielberg (who was raised Jewish and has become more observant in recent years) was filming ET: The Extraterrestrial, someone pointed out to him the parallels between ET and Jesus. (Arrives on our world from the sky ... Heals people by touching them... Has glowing red heart... Dies but returns to life, then ascends... Protestant readers might add, "He and his friends persecuted and driven into hiding by bad guy who carries a set of keys".) Spielberg's response was "Look, I'm Jewish, I don't want to hear about this".
Deeply ironic: Two of American popular culture's most instantly recognisable figures, both close analogies of Jesus, both created by Jews.
UPDATE 1: And yes, I know Jesus and disciples were Jews too, of course. But I'm talking 2,000 years later, now that Christianity and Judaism have diverged into two very different religions, after centuries of (some) Christians calling Jews "deicides" and (some) Jews echoing Maimonides' sentiment: "Jesus of Nazareth, may his bones be ground into dust..." And while Christianity and Judaism share many points in common, those are not the points that either ET or Superman exhibit: descending from the sky, using super-human powers, etc, are specifically Christian rather than Jewish attributes of a Messiah.
UPDATE 2: My impeccable source informs me that ha-Thing is not in fact the first Jewish superhero, nor even the first for Marvel. Katherine "Kitty" Pryde, a.k.a Shadowcat/ Sprite of The Uncanny X-Men, was identified as Jewish years ago. (Don't ask me how: not being a Democrat Congressperson or a Guardian columnist, I don't possess finely-tuned Jewdar capable of detecting hidden Hebrews in unexpected places). Perhaps Kitty was ethnically Jewish but non-practising, whereas Ben Grimm is the first to actually practice the rituals of Judaism (eg, reciting the Shema) on Marvel's pages.
(And when The Thing takes on The Hulk, the resulting orange vs green blur is a metaphor for Nothern Ireland...)
UPDATE 3: It turns out there are plenty of other Jewish superheroes. Here (via The Volokh Conspiracy) is a long list.
In any case, from my (medium-level) reading I don't think many superheroes (as distinct from kindly adoptive parents who bake great Thanksgiving pies) are really religious in any meaningful sense. The Catholic ones I mentioned tend to be tormented by guilt -- as you would too, if you either looked like a devil or dressed like one -- and to spend a lot of time hanging around churches, but otherwise aren't distinctively Catholic. They don't, for example, ask themselves whether letting the bad guy fall to his death from a cliff edge, because he refuses the hero's helping hand, counts as "direct or indirect formal or material complicity with homicide" pursuant to the Doctrine of Double Effect. Nor, for that matter, can I picture, say, Peter Parker asking himself "WWJD?" before deciding whether to continue hot pursuit of Doc Ock, or pause to stop a granny being run over.