Father Ted writer Graham Linehan says the spirit of his best-known show motivated him to back the atheist advertising campaign launched earlier this week.
Linehan unveiled one of the four advertisements set to feature on the London Underground at the launch of the adverts in Hyde Park on Tuesday.
And as he explained to inthenews.co.uk the spirit of Craggy Island was "never anything but what we're saying today".
"Arthur [Mathews,] my writing partner on Ted, always used to say if you take what the Catholic church is saying literally you'd go mad," he said.
"Because the world is so bizarre you wouldn't be able to function, you know. So I guess this is just an extension of that sort of thing."
Linehan said he immediately signed up to be part of the launch when told the quote he would be unveiling was Emily Dickinson's "that it will never come again is what makes life so sweet".
Around 800 buses across Britain will bear the message: "There's probably no God. Now stop worrying and enjoy your life."
Linehan, who has been an atheist throughout his adult life, said he would have refused to support it had it been more "fundamentalist" in approach.
"I don't think that's a really good way to behave because it's taking the tactics of the people we're sometimes fighting against fundamentalists of whatever stripe," he told inthenews.co.uk.
Linehan, whose latest creation The IT Crowd saw its third series broadcast on Channel 4 before Christmas, threw his weight behind the adverts' message, however.
He said: "It just seemed to be to be such a positive, optimistic sweet thing to say that I thought I couldn't not support it."