Probability—the essence of God’s power—dictates that the penny must sometimes come up tails even when the penny chooses to be heads (page 64)
When things don't go as planned we see God's will at work and when things do go as planned we see our will at work (and fail to see God's).
This is kinda a good compromised of the wills. God is in complete control, even thought people think they sometimes are. Depending on how hard you push this idea, it may lead up to a deterministic idea that God has strict control over everything and we really don't have free will. If we don't have free will, then are we really guilty of anything?
Some simple answers are not necessary true, and in fact may cause more hard questions.
At the moment I am trying to read up about this. Since this free will issues came up, I am not quite sure where I stand now. I read about a guy some guy called Hasker (I don't know his first name) on a blog (and here as well) . The posts are hefty and I'm not sure I really understand them. Determinism is split into hard and soft (compatibilism) categories, and events that happen to people still makes them morally responsible, as determinism and free will are incompatible. There are some others that don't like Haskers views.