A video clip of the famous atheist describing what he would say if he got to heaven has gone viral online.
In an interview with Irish broadcaster RTE, he said: "I'll say 'bone cancer in children - what's that about? How dare you. How dare you create a world in which there is such misery that is not our fault. It's not right, it's utterly, utterly evil.'
"Why should I respect a capricious, mean minded, stupid God who creates a world which is so full of injustice and pain."
The comedian's attack on the Christian faith has had over two million views on YouTube.
He is then asked if he thought he would get into Heaven and replied: "No, but I wouldn't want to. I wouldn't want to get in on his terms. They are wrong."
He added: "Because the God who created this universe, if it was created by God, is quite clearly a maniac, utter maniac. Totally selfish. We have to spend our life on our knees thanking him?! What kind of god would do that?
"Yes, the world is very splendid but it also has in it insects whose whole lifecycle is to burrow into the eyes of children and make them blind. They eat outwards from the eyes. Why? Why did you do that to us? You could easily have made a creation in which that didn't exist. It is simply not acceptable.
"It's perfectly apparent that he is monstrous. Utterly monstrous and deserves no respect whatsoever. The moment you banish him, life becomes simpler, purer, cleaner, more worth living in my opinion."
"And the answer is, of course, that he shouldn't, he mustn't, respect such a deity. And neither do I. Let's not leap to defend a god we don't believe in. We have a name for a 'capricious, mean-minded, stupid' being, but it isn't 'God'"
He added: "Of course, none of this would convince Stephen Fry. Arguments rarely change anything and I'm hardly in his intellectual league.
"But I'd love to take him to meet some of my friends who are hospital chaplains and aid workers and counsellors and priests.
"They work amongst those who are sick and suffering, and would tell him in no uncertain terms how Jesus often brings such people unspeakable hope.
"Multi-millionaire celebrities may rail against the injustices of life, but meanwhile the poorest, most oppressed people on earth frequently exhibit resilient faith in the goodness of the God Stephen Fry currently rejects on the basis of the tragedies they themselves endure."