A judge dismissed the suit a writer named Saint Solomon filed against AS. He claimed their show ripped off his short story, "Thank You, Jesus" -- which also features an African-American Messiah.

In the docs -- obtained by TMZ -- the judge spells it out pretty clearly -- the tales of 2 Christs aren't similar at all ... other than the lead characters being black.

Yes, both works had the idea of making Jesus black, but as the judge said, "Ideas are not protected by copyright."

As we reported ... Solomon wanted $75 million from Adult Swim. No dice.