He already tried that

Someone asked why God did not put some more obvious proofs of his existence in the Bible. He could, for example, have given the millionth number of π and asked mankind to check it out, once we had developed computers to calculate it.

Well, he actually did try it. He did write it down. He also explained that the moon was not made of cheese and that the Einstein-Podolsky-Rosen paradox did not contradict quantum theory. The problem was that the early editors of the Bible had no idea what he was talking about, so they thought it was a typo and removed those paragraphs.

It is a good point though, and perhaps it is time for a new edition of the Bible with some new information that hitherto has been hidden for man. He could for example explain string theory or write down where I left my car keys this morning.