It is said that God knows all contingencies, but none of them contingently. God never says to himself, “That depends.” Nothing is contingent to him. He knows all things that will happen because he ordains everything that does happen. This is crucial to our understanding of God’s omniscience. He does not know what will happen by virtue exceedingly good guesswork about future events. He knows it with certainty because he has decreed it.
Sproul, R.C.; Grace Unknown: The Heart of Reformed Theology; Baker Books; Grand Rapids, MI; copyright 1997; p. 172