I feel I've reached my bi-annual quota of writing such pieces myself, so I'll link to somebody else's column, instead.
From the column:
Superman isn’t a Jesus analogue because, unlike Jesus, his moral vision is not imposed. The word of Jesus is the word of God2 and therefore what he says goes, dictation straight from the Almighty. Superman is the exact opposite: a man whose moral vision comes not from a source exterior to humanity but from humanity itself, via Ma and Pa Kent, who are themselves immensely decent people. He ultimately isn’t a received savior, regardless of the origin of his powers; he’s Superman, the apotheosis of what human virtue can be. He’s an aspirational figure first and foremost.3 There’s a reason people get S-symbol tattoos; they have meaning in a way that other superhero images just don’t.