For breakfast next Tuesday, John will have either ham or jam. That's all John ever has for breakfast, ham or jam.
John will freely choose between ham or jam on Tuesday, iff both ham and jam are legitimately possible future realities for John.
At the moment of creation, however, God knows infallibly that John will have ham for breakfast on that Tuesday.
Infallible knowledge cannot possibly be wrong. When God knows infallibly that John will have ham, it is not possible for John to have jam. If it were possible for John to have jam when God knows he will have ham, then it would be possible for God's knowledge to be wrong. This is a contradiction.
Therefore, when God knows infallibly the future states of the universe no alternative states are possible, and therefore, despite any and all appearances, free will cannot exist.