Found this quote:
God’s omnipotence means [His] power to do all that is not intrinsically impossible. You may attribute miracles to Him, but not nonsense. This is no limit to His power. If you choose to say, “God can give a creature free will and at the same time withhold free will from it”, you have not succeeded in saying anything about God: meaningless combinations of words do not suddenly acquire meaning simply because we prefix to them the two other words “God can.” It remains true that all things are possible with God: the intrinsic impossibilities are not things but nonentities. It is no more possible for God than for the weakest of His creatures to carry out both of two mutually exclusive alternatives — not because His power meets an obstacle, but because nonsense remains nonsense even when we talk it about God. -C.S. Lewis
I like this quote, it’s a piece of very sound rationalism. Remembering this can keep us from holding on to some of the silly ideas we come with about God. However, that’s all it is: rationalism. It can only be applied correctly to the degree that you really understand what you are talking about. Watch out, for the free will of God’s creatures is a deep and rather mysterious thing; a confusing thing when viewed from the perspective of the creatures (us). It would be wise to reckon there is more to it than you may grasp.
Someone with a straight-forward view of predestination would look at this quote and say, “Well of course. Duh! Is God in control? Well, yes, of course he is. So your not. They’re mutually exclusive. End of discussion.” That’s pretty sound now, isn’t it? Except wait. God’s sovereignty versus our free will is a false dichotomy. It’s possible to have both (in some way), because they are apples and oranges. Now what way is that? It’s a mystery.