I'm no expert on any of these things, but recently I read a book by Harold Bloom called Omens of Millennium (New York, 1996) that claimed Zoroaster, the Iranian prophet who may go back as far as 1500 BCE, "invented the resurrection of the dead." Before him, says Bloom, most of the dead passed to an unpleasant underground existence, except for a few chosen by the gods for something better.
Zoroaster apparently refined this notion by inventing heaven and hell, as we think of them today, with true believers going to the "skies" and unbelievers being punished in an underground after-life. The prophet believed in a "divine fire" that was expected in his own lifetime to change "nature" into "eternity." Thus far, this sounds like the same theological hogwash we're all so familiar with.
But I do like how this concludes, for Zoroaster prophesied a savior, Saoshyant, who "will prevail against all evil forces, and who will resurrect the dead." It's hard to know what to make of this, but one thing seems clear enough: the Christian invention of Jesus as the savior who could resurrect the dead wasn't even an original thought.