Again, why is it an issue that God knows everything? What God knows is not the cause of anything that happens, all-knowing is an attribute of God.
Let's just ignore God for the moment, so we now live in a Universe without God or any supernatural things.
If we compare the two setups, a nondeterministic Universe vs a deterministic Universe and we use the same idea as before with the pictures of the Universe and Johnny.
nondeterministic
T(0) --> T(1) --> T(2).......T(Now) --> T(Future)
T(Future) is based on whatever Johnny decides at T(Now). But no one knows the exact sequence in the future, it will change based on what Johnny decides, so he might go to University or he might join the military.
That means that T(Future) can't be fully known, because it depends on Johnny's choice. We can predict the future in certain cases, like the position of planets etc. because we know the physical circumstances around it, speed, mass, and whatever is needed to predict the movement of objects, but we don't know what Johnny will decide, only he does when he makes the choice.
So given the sequence isn't known, that means that Johnny's choices/actions (Free will) will influence the future.
Deterministic
Will do this shortly since we have talked a lot about it.
T(0) --> T(1) --> T(2).......T(Now) --> T(Now+1) --> T(Now+2) --> T(Future)
If the sequence is deterministic, then whatever Johnny does, has to align with the next image meaning that whatever he does, it will always end up in T(Now+1), because that is required to get to T(Now+2).
So if T(Now+1) is Johnny joining the military, then Johnny can't choose to go to University at T(Now), yet Johnny might get the impression at T(Now) that he is about to choose between the military and University and him choosing the military was his own free will choice, but it is nothing but an illusion because he has to end up in T(Now+1), it is already determined beforehand.
So the difference between the two setups, is that in the nondeterministic one, Johnny's choice/actions (Free will) influence the future of the Universe, whereas in the deterministic one, nothing Johnny does influences anything, it is happening in the exact way as the sequence dictate it will.
Keep in mind, we are purely talking about a Universe without God or any supernatural things because it doesn't matter.
It is purely a question of whether we live in a deterministic Universe or not, which there are different opinions about, but again, you don't need God to have this discussion, but that is not what we are trying to solve here
But the reason why God is irrelevant for this, is because we aren't sure whether we actually have free will or not.
For instance, if you read this:
Published in the prestigious Nature journal today, an experiment carried out in the Future Minds Lab at UNSW School of Psychology showed that free choices about what to think can be predicted from patterns of brain activity 11 seconds before people consciously chose what to think about.
The experiment consisted of asking people to freely choose between two visual patterns of red and green stripes – one of them running horizontally, the other vertically – before consciously imagining them while being observed in a functional magnetic resonance imaging (fMRI) machine.
The participants were also asked to rate how strongly they felt their visualisations of the patterns were after choosing them, again while researchers recorded their brain activity during the process.
Not only could the researchers predict which pattern they would choose, they could also predict how strongly the participants were to rate their visualisations. With the assistance of machine learning, the researchers were successful at making above-chance predictions of the participants’ volitional choices at an average of 11 seconds before the thoughts became conscious.
The brain areas that revealed information about the future choices were located in executive areas of the brain – where our conscious decision-making is made – as well as visual and subcortical structures, suggesting an extended network of areas responsible for the birth of thoughts.
However, the researchers caution against assuming that all choices are by nature predetermined by pre-existing brain activity.
“Our results cannot guarantee that all choices are preceded by involuntary images, but it shows that this mechanism exists, and it potentially biases our everyday choices,” Professor Pearson says.
If whatever we do is decided before we are consciously aware of it, it raises some questions about free will. an average of 11 seconds is quite a long time.
We as humans don't experience this, when we have a thought it appears to us instantly, meaning we experience it as being instantly consciously known to us. This would mean that Johnny decides to go to the military might already have been decided 10 seconds before he himself is even aware of it, but to him, it appears to be his own choice.
This is quite interesting in itself, how the hell does the brain do this without us being consciously aware, the brain is after all part of us? It seems like nonsense that it is even remotely possible.
Now let's try to bring back God
When you say that God knows everything, that means that he knows this sequence:
T(-1) --> T(0) --> T(1) --> T(2).......T(Now) --> T(Now+1) --> T(Now+2) --> T(Future)
The problem is not that God knows it, the problem is that by saying that God (anyone/anything) knows it, automatically means that you jump to the conclusion that the sequence is determined. Again let me stress it, this is also true even without God (You, me, your cat would do just fine as well).
You seem to get stuck at God (Someone) knowing it, it doesn't matter, nothing could know it and it could still be deterministic, simply because T(2) is decided by T(1), at a much lower level than we humans can comprehend, if it is based on how atoms interact with each other, based on physical laws, then we do not influence it, things happen because of how these atoms interact, so just as planets orbit the sun in a predictable way, so will everything we do, we simply don't have the abilities yet to make these predictions, yet the study above, seem to indicate that at least in certain cases, we can actually predict what humans do even before they are themselves aware of it.
Try to first think of it without including God, simply ignore him. If you can see how this could be true without God, then adding God makes no difference, except that in a Universe without God, no one is currently claiming with 100% certainty that this sequence is known, compared to when you add God and then conclude that he knows with 100% certainty, then there can't be free will.