Notes on first page of Diary

Here the author is attempting to justify his claim that God is absurd:

His answer is that God, as what we can not know, cannot have meaning or purpose because we can never know what they might be, and not being able to know something means that it doesn't exist, or at least we cannot know that it exists which the author believes is sufficient for, although he doesn't write anything of the sort, asserting that something's non-existence.

But questions have arisen from this: if absurd can also mean 'having no sufficient reason for being', can we say that God has no reason for being? If God is not, God can still have a reason for being: to give hope through the prospect of the afterlife, to grant redemption from sin and guilt, etc... And these are sufficient. But we cannot know that God does this, rather than the priests, because we cannot know God. Then: Can what we cannot know have a sufficient reason for being? I will leave this open...