He can't read your thoughts, but he can guess what you're thinking. He can predict what you're going to do next, based on your previous actions. He knows if you're thinking about sin. He knows when God is on your mind. He knows your secrets. He was there when it happened. A journal won't help him in anyway to get access to your mind. If your mind isn't with God, then he already has access to it.
Comments
I say you keep a journal anyway; they're useful.