In a universe where foreknowledge is possible, the future must be set; therefore the event precedes knowledge logically but not chronologically. Thus the future is not set (determined) by the knowledge in question, but rather by whatever factors are said to determine events generally (e.g. decisions, previous events, the butterfly flapping its wings).
None of this is clear to me. You say the future is set because of foreknowledge but then the future is not set by foreknowledge but by other factors. Well, which is it? How is it that the event would precede the knowledge logically? I don't find this a coherent explanation because if the knowledge precedes the event chronologically then it cannot be said that other factors determined the event.
If the event is not in some sense actual then the future cannot be known and foreknowledge as a concept is jabberwocky. The future is not yet a present reality, true, but the future must be said to "exist" or "be real" in a way that allows foreknowledge to be possible.
All I'm saying is that the event doesn't exist as an actuality just yet, however that doesn't mean the event wouldn't "exist" conceptually and necessarily in the mind of God. We cannot confuse the meaning of existence here, as the event again wouldn't "exist" as an actuality when God foreknew of it.
For the purposes of this conversation it is only necessary for me to point out that many Christians disavow the belief in divine infallibility and as such cannot be presumed in an argument for foreknowledge.
I'd recommend leaving divine infallibility as a condition of the argument because it is complex in its own right and cannot be done justice as a subset of our own conversation.
Then I can point out the same, that many Christians do not believe God is fallible. And this is why we cannot leave infallibility out of the conversation: You've already agreed that the foreknowledge of God cannot be incorrect, as that is what it means for God's foreknowledge to be infallible. If God's foreknowledge cannot be incorrect, it is infallible knowledge of the future.
To you, does saying the future MUST happen the same as saying the future WILL happen? If yes, then I disagree with the above. If no, then I probably agree with the above.
Yes, what God foresees in the future will happen. Again we can only say that the future will not happen or something other than what God foreknows could happen unless God's foreknowledge is incorrect, a premise to which you already said is contradictory to the concept of foreknowledge.
Free will cannot be defined on these terms, because that means if I want to fly and gravity stops me, free will is immediately disproven.
Is it? I do not think it is as immediate as you think. I think you missed my definition of free will or perhaps have misunderstood it. I've defined it as
the ability to do what we want or please. We do not have the ability or power to fly, so free will wouldn't be applicable in this situation. Put it this way:
Do you think because of your inability to fly that you could be held morally accountable if you do not fly when attempted to do so?
I am guessing you would think not. So if we cannot apply moral responsibility in respect to the laws of nature, neither can we with free will. Just because we cannot hold our breathe under water if we wanted or cannot fly doesn't mean one could not be free. You're basically confusing our ability and power to do something with a physical necessity or impossibility given the laws of nature.