The Atheist's God

In a book titled "Orthodoxy," G. K. Chesterton wrote:

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.