Does God know the future?
I think it is less problematic to suppose that God does not exist in space/time. The alternative would, I think require that God were a part of the physical universe, with many of the limitations which that would involve.
The consequence of that is that God does not experience what one might describe as the flow of time, though he does understand that the material universe does exist in space time. There is no stage of the temporal process which is ‘now’ for God.
Aristotle poses a famous conundrum about tomorrow’s sea-battle. Can it already be true that there will be a sea-battle tomorrow, even if the naval commanders have not yet made up their minds? He would wish to argue first that it must already be true either there will be such a battle or there will not: and if there will be such a battle, that statement must be true now. Truth is concerned with what is the case, whether in the past or the present or the future. God timelessly <knows> --take the angle-brackets to contain a non-tensed verb—whether there will or will not be a sea-battle tomorrow, as just as he <knows> whether it is true or false that I shall die in 2020.
This is not fatalism. Many statements about the future are true because of what people will freely do tomorrow; those who are responsible for shops and buses and trains depend on having as correct estimates of the future as they can.
It follows that God <knows> what I shall do next Saturday; and, in my view, God <know> it not because his knowledge somehow makes me do it; God knows it because that is what I shall do. It is my free choice which provide the knowledge that God timelessly <has>about me.
Gerard J Hughes SJ