The Lewis "space trilogy" was about a man named Ransom who visits Mars and Venus, having been kind of hijacked into the trip. The books are interesting and imaginative.

The gist of the story is that God has several intelligent races in his basket, but only Earth of these three worlds has "fallen" and had to be redeemed by an incarnation of God as a human. Earth is still "the silent planet," cut off from the spirituality that is the norm elsewhere. The first book is about Mars, which possesses more than one intelligent native species. They live in peace and harmony with God and each other, never having "fallen" into sin in the first place. In "Perelandra," Ransom is recruited by the "powers that be" to go to Venus where the first man and woman have been placed in that planet's Eden (at that time it was still okay to present Venus as an ocean world). Ransom's job is to prevent the devil from wrecking Venus, too.

It's a lot of fun, with some theological speculation thrown in.

After all, who's to say the aliens won't have something to teach us about God?