As an atheist, of course, I don't believe in any gods so what I'm discussing here is the god of the Bible, whom Christians, Jews and Muslims all believe to exist and who is at the centre of their belief system.
This god is generally assumed by all believers to be inerrantly omniscient, i.e. it knows all things, including, in absolutely inerrant detail the entire future of the Universe and everything in it - every celestial body, every living thing, every atom and every particle. This god could, if it was so inclined, tell you with absolute accuracy, the position of any given electron at any point in time, past or future.
This god, so its followers claim, has also granted mankind free will, so that we may determine our own destiny and so we are fully accountable for our actions. God has not pre-ordained anything at all, so far as humans are concerned. He is a mere observer of our actions and we are only accountable to him for them at some later date.
Well, let’s explore the idea of omniscience and free-will. Let's assume that God knows (with inerrant certainty, remember) that you will have eggs for breakfast tomorrow. Can you then decide to have cereals, or anything at all other than eggs?
If yes, doesn't that mean God's 'knowledge' of your future was wrong? How can that be if God is inerrantly omniscient? If no, then in what sense of the word do you have free will?
"Ah!" You might say, "God knows what my choices are, not what I will choose". In that case, does God simply know the range of all possible futures, but not the actual detail? If so, this is some way off inerrant omniscience, isn't it? In fact, it would probably not be beyond the wit of anyone who knows you and your culture to make a reasonably accurate forecast of the range of possible choices you will have for breakfast tomorrow. Nothing really special in that skill at all when you think about it.
No. There is absolutely no way to square this circle. Either you have free will or God is inerrantly omniscient, not both. Free will and an omniscient god cannot logically exist in the same Universe.
If you can see a way round this, feel free to post it here. Remember though that mere opinion isn't a valid argument. Please confine yourself to the logic of the problem.
Now, let's explore the proposition of God's inerrant omniscience a little further to see where it leads. We've already dealt with your free-will (or rather the lack of it) in choosing breakfast tomorrow in the presence of an inerrantly omniscient god, but what of other choices, not only for you but for everything else? And what of God's OWN freedom to choose?
If God knows and has always known every minute detail of the future, how can he change his mind and still be inerrant? Of course, he can't otherwise he will render himself errant. In fact there would be no logical way that this god can even decide to make a decision since he would have known of that event, and its outcome for all time. An inerrantly omniscient god cannot even decide to decide something, let alone influence anything. Everything in the universe in which an inerrantly omniscient god resides would be absolutely and unchangeably pre-ordained.
Such a god in such a universe would have absolutely no purpose. For all practical purposes it would not exist. There would be no difference between that universe and one in which there is no god.
By now, if you believe in God, you're probably thinking you see a logical fallacy here. You're probably thinking that this god, by its inerrantly omniscient knowledge of the future, brought the Universe into existence and it could not have existed without it.
But think on. How could this inerrantly omniscient god have even decided to bring the Universe into existence? How could it have decided to plot the future of all things? The fact of its inerrant omniscience renders it completely paralysed, unable to move, unable to decide anything, unable even to think, since all its own actions, even the actions of its own thought processes are also fully and unchangeably pre-ordained. Nothing in the universe occupied by an inerrantly omniscient god can be changed, not even the thoughts of that god itself. In fact, such a god might as well be an unthinking rock on some remote planet orbiting a sun in some distant galaxy, functionally indistinguishable from any other rock on any other planet in any other galaxy.
And, paradoxically, since this god could not have created the universe in the first place, a universe occupied by an inerrantly omniscient god could not have been created by it.
The logic of an inerrantly omniscient god not only means you cannot have free will, it also means that such a god, for all practical purposes, does not exist and could not have created the universe.
Conversely, any creator god cannot be omniscient and inerrant like the one described in the Bible the Torah and the Qur'an.
Please feel free to point out the logical errors in the above reasoning.