Superman may or may not be Christ, depending on who you ask.
There are perhaps more books and articles concerning Superman's connection to Christ than there are on any other Superman topic. It all seems to have begun with John T. Galloway, jr.'s The Gospel According to Superman, fixing a title that has probably frustrated other authors since it's 1968 publication. This book set out to prove once and for all that Superman is certainly not Christ, and that claiming him to be so is damaging. It explores the character's actions and history and ultimately concluding that Superman is in no way like Christ.
This was before the 1978 movie.
After that movie, articles began springing up proclaiming Superman's Christ-like-ness. It was all very deliberate on the part of director Richard Donner and one of the writers, Tom Mankiewicz. They saw the parallels in the stories and made them explicit, most famously during Jor-El's speech to Superman as the baby travels to Earth:
"They can be a great people, Kal-El, they wish to be. They only lack the light to show them the way. For this reason above all, their capacity for good, I send them you, my only son."
As a kid of 1 when this movie came out, I completely ignored the subtext there.
So soon after you've got Sarah R. Kozloff's "Superman as Saviour: Christian Allegory in the Superman Movies" (from the Journal of Popular Film and Television, 1981). People saw the parallel, and it either made them happy or mad. Apparently the director got death threats.
Then there's The Man from Krypton: The Gospel According to Superman, by John Wesley White. I haven't read it yet, but it's on its way to me even as we speak.
More recently, there have been lots of these. I suspect the more obvious Christian imagery in Superman Returns and the widened audience for it provided by the internet has sparked the books and articles.
Anton Karl koslovic's "Superman as Christ-Figure: The American Pop Culture Movie Messiah" came ahead of the rush in 2002 in the Journal of Religion and Film. He's all for the subtext, as it points toward Christ.
There's Stephen Skelton's The Gospel According to the World's Greatest Superhero. There's Ken Schenck's "Superman: A Popular Culture Messiah" in the book The Gospel According to Superheroes, edited by B.J. Oropeza. There are chapters in books such as Holy Superheroes by Greg Garrett, and H. Michael Brewer's Who Needs a Superhero? about this sort of thing.
Sort of Related are books such as Christopher Knowles Our Gods Wear Spandex and Don LoCicero's Superheroes and Gods. Both of these books look for early parallels (which they see as forerunners) to superheroes in myths and legends, not specifically in Christ. They both devote some pages to Superman. Also in this category I'd put Josepha Sherman's Once Upon a Galaxy, which does the same thing with various films and has a chapter on Superman.
Aside from a score of newspaper articles and hundreds of blogs and other websites, that's about it. People like to point out how similar Superman is to Christ, and then they like to argue about it.
I actually have a lot more to say about this, as you may expect. I sat down to take what I thought would be a page of notes and found myself with eight pages of a chapter, and I hadn't even gotten to Christ yet. So, no real commentary or analysis here, but there will be a bit in the book someday, I hope.