G‑d knows all before it occurs. More than that: It is His knowledge that brings all events into being.
But we still have free choice.
You claim this is inconceivable. I ask you: Knowledge of all existence before even the thought of existence is conceivable?

Existence Our problem is that we try to look at existence objectively, while the nature of our existence is subjective. Acceptance is the key to our conundrum: the beginning of wisdom is fear of G-d.