My previous post got me thinking about the religious symbolism of Superman. Siegel and Shuster's origin of the character was undoubtedly a cosmic analogue merely of baby Moses in a basket escaping infanticide, so I think it is probably the Catholic Mario Puzo's screen adaptation which is primarily responsible for the "Christianization" of Superman's Jewish origin story:
Jor-el is the Father who banishes a traitor and his followers from the heavenly Kryptonian paradise into a Phantom Zone hell, then sends his Son to Earth (in Johannine language and via a Nativity Star-ship) to be its savior, who is raised by humble surrogate parents (and whose earthly father dies), and as an adult retreats to the (Arctic) wilderness before beginning his "ministry" at age 30, whereupon he reveals himself to the world by performing miracles (later including raising his friend Lois/Lazarus from the dead), is tempted by Lex/Lucifer who offers him earthly riches if he will serve him, and refues, but is momentarily defeated and placed in a (watery) grave, a death which is accompanied by earthquakes, then rises again, et cetera. (I can only imagine the metatextual implications if Jim Caviezel had actually been cast in Superman Returns, as Mike Millar famously wagered for $1000 in August 2004.)
Puzo could be accused of being over-ingenious, but once the analogy was depicted in 1978 it could never be ignored again. The miracle is not only that he managed to do it without violence to the history or personality of Superman but that it became the iconic version of the character.
Not only did Byrne draw on it for his version of Krypton in the 1986 reboot, but by his desire to make Superman an American citizen by birth, not adoption, he also (intentionally or not) diminished the Mosaic parallel in favor of the Christian nativity by making Kal-el emerge from his gestation matrix on terrestrial soil, paradoxically making him both Kryptonian by nature and a native of Earth.
In his final-page soliloquy (though actually shown in thought balloons) from The Man of Steel #6, Byrne's Superman concludes his self-reflection with an almost Chalcedonian expression of his dual nature: "It was Krypton that made me Superman . . . But it is the Earth that makes me human!!"
Unfortunately, what this revision of Superman compromised was the significance of his original status as the ultimate immigrant who chooses to stay on Earth. Being an American citizen by birth undermined the virtue — and sometimes tragedy — of his choice to personally associate with humanity. Among other things, Clark Kent should represent Kal-el's deep desire to assimilate into human culture, always an integral aspect of Siegel and Shuster's story, written when Jews — like Superman, without a homeland in 1938 — were being further segregated in Europe. Superman gives us hope that even the most alien of us can achieve integration.