Because an omniscient being already knows the outcome of each person's life. An omniscient being cannot be fooled, because that would contradict its very existence.
So if he does have the ability to change outcomes, why doesn't he? Why isn't everyone in the world Christian? Because your god is fake.
(You've got to stop acting like you made a solid argument after each response. You aren't, and it just looks sad when you're repeating the same things over and over without thinking of a decent response.)