[...] Chesterton is fully aware that it is not enough for God to separate man from Himself so that mankind will love Him — this separation HAS to be reflected back into God Himself, so that God is abandoned BY HIMSELF:
When the world shook and the sun was wiped out of heaven, it was not at the crucifixion, but at the cry from the cross: the cry which confessed that God was forsaken of God. And now let the revolutionists choose a creed from all the creeds and a god from all the gods of the world, carefully weighing all the gods of inevitable recurrence and of unalterable power. They will not find another god who has himself been in revolt. Nay (the matter grows too difficult for human speech), but let the atheists themselves choose a god. They will find only one divinity who ever uttered their isolation; only one religion in which God seemed for an instant to be an atheist.2
Because of this overlapping between man's isolation from God and God's isolation FROM HIMSELF, Christianity is "terribly revolutionary. That a good man may have his back to the wall is no more than we knew already; but that God could have His back to the wall is a boast for all insurgents forever. Christianity is the only religion on earth that has felt that omnipotence made God incomplete. Christianity alone has felt that God, to be wholly God, must have been a rebel as well as a king."3 Chesterton is fully aware that we are thereby approaching "a matter more dark and awful than it is easy to discuss /.../ a matter which the greatest saints and thinkers have justly feared to approach. But in that terrific tale of the Passion there is a distinct emotional suggestion that the author of all things (in some unthinkable way) went not only through agony, but through doubt."4 In the standard form of atheism, God dies for men who stop believing in Him; in Christianity, God dies for himself.
2 Chesterton, G. K, Orthodoxy, San Francisco: Ignatius Press 1995, p. 139.