Well, at least "Personal Jesus" kinda works in a gospel context if you read it as aspirational (think "WWJD"). "Spirit in the sky" on the other hand is New Age at best and cynical parody at worst -- the entire idea behind that song was "gospel songs seem easy to write, I bet I could do that".
I guess it's the musical equivalent of Poe's law: it's over the top and a bit insencere but the medium it mimics is already so over the top it fits right in and nobody bats an eye.