Here's a thought. Why not put the "Tree of Knowledge" on the Moon, or Mars, or even somewhere around Proxima Centauri? Then when we finally man up as a species to get there and find it, "God" would know we were probably mature enough to handle the knowledge of "his" existence. As Browning put it, a man's reach should exceed his grasp; or what's a heaven for?
At the age of five, Skagra decided emphatically that God did not exist. This revelation tends to make most people in the universe who have it react in one of two ways - with relief or with despair. Only Skagra responded to it by thinking, 'Wait a second. That means there's a situation vacant.'