God loses no power by not knowing everything. God can both know everything and know nothing. in order for other Spiritual Beings to exist spiritual Freedom other than Gods Must exist. By God's Act of denying himself he creates a void for other beings to be. God, who is the Divine abyss, contains all other abysses inside of himself. Since he can Encompass all other beings he has no need to fully know the future. But he does know that all comes from him, and so he does not fear the future.
That's my mystical take on it.