And how am I to know it is God?
How do you know anything? How do you know I am really here? How do you know if you are actually at your computer now? You could be in a hospital bed in a coma dreaming it all. Rationally, any of those are perfectly possible, and perfectly arguable. On balance, you operate on the premise that they aren't so and that the world is as you see it. You have to do that, otherwise you would never do anything. You can run, you can hide, you can prevaricate and you argue, but you are operating on faith (irrationality and illogicality, if you want to call it that). Similarly, in your dealings with God, it is a leap of faith that is required.