Here's my suggestion: "There may or may not be a Divine Being or Beings, and they're probably just the anthropomorphic interfaces of vast cosmic processes, but anyway, they're on their own spiritual journey and their goals may or may not coincide with yours. They certainly can't be bothered to arrange for you to fry for all eternity on a hot griddle, so you can stop all that worrying."
But perhaps the above is not as snappy as the Atheist Bus.
Liz Williams suggests:
GOD: SHE'S NOT JUST AN OLD BLOKE WITH A BEARD, YOU KNOW!Another suggestion from KH:
"Zeus is going to kick your pussy God's ass and then shag your women!"Maybe we could just have a poster on the side of buses that reads: "Paganism: the religion where enjoying yourself is SACRED." Except that we don't believe in evangelising.
(Also available in Judaism, where it's a sin to refuse a pleasure, apparently, and it's requirement to make love on the Sabbath eve; and Unitarianism, which celebrates being alive.)
All this talk of buses reminds me of the short story by E M Forster, The Celestial Omnibus, which you can hear read aloud at the Library of Babel.
The title-story is a whimsical piece of fantasy which again uses a child as the means to unmask unimaginative adult pragmatism. “The Celestial Omnibus” starts with a young boy who is perplexed by the sign-post in his Surbiton street that says “To Heaven” and points to a cul-de-sac. Running up the blank alley one evening he encounters an omnibus which takes him up to a paradise where he meets all the characters from fiction and mythology that his parents and their friends talk about but do not really believe in.