Zelazny riffed on more than Genesis; the setup is the Book of Job (can man be tempted out of his faith) and the plot is Faust (what does selling your soul to the devil really mean).

The story itself is an exploration of what it means to be human. Zelazny goes through a lot of pretty, allegorical scenery in order to arrive at the conclusion that it isn't action that makes a human, it's the motivation behind the action. It isn't the irrationality, it's the willingness to act on the irrationality. For whatever reason, it isn't until Frost is in meat that this comes to the fore - prior to that, he's still a machine intelligence. After, he's a scared organic intelligence trapped in silicon.

I think it's also worth noting that Frost is the first thing any of the other robots respect as having "free will" - another touchstone that Zelazny integrates. Frost, after all, was made sort of by accident. There's a "divine spark" in his makeup that is missing in everything else.

Yet there was something different about Frost, something which led Solcom to dignify him with a name and a personal pronoun. This, in itself, was an almost unheard of occurrence. The molecular circuits had already been sealed, though, and could not be analyzed without being destroyed in the process. Frost represented too great an investment of Solcom’s time, energy, and materials to be dismantled because of an intangible, especially when he functioned perfectly. Therefore, Solcom’s strangest creation was given dominion over half the Earth, ad they called him, unimaginatively, Frost.

One of the themes in Zelazny's writing is that not only is God dead, but he was never more than a figment of our imagination. Despite being a figment, however, he is not without powers. Solcom made Frost because Solcom makes things; Frost entered a Faustian bargain because Frost is.

I think it's always been one of my favorite stories because it's the most deeply optimistic post-apocalyptic tale I've ever read. Even with humanity thousands of years dead, there's still room for rebirth and romance. It's got a delicacy that Asimov or Heinlein or Clarke never had, and he's got a point which has always been my beef with Bradbury.

And he's not a mean, cantankerous people-hater like Ellison.