What is the significance of Genesis 22:12 ?

Abraham passed God’s “test” (vs. 1) by being willing to sacrifice his son. The Lord says “…now I know that you fear God, since you have not withheld your son…”

If the classical understanding of foreknowledge is true, God’s statement “now I know” seems disingenuous. The meaning of God’s explanation for this knowledge — “since you have…” — is also obscured. Indeed, if the future is exhaustively settled there would be no point in his test of Abraham, because God would never have to find out anything.

Defenders of the classical view of foreknowledge usually argue that God’s testings were not for his sake, but for the sake of the person being tested. God eternally foreknew whether or not the person(s) would pass the test, but he wanted the person’s character to be manifested to them. This explanation sounds plausible except this verse explicitly records God proclaiming “now I know…” Other verses contain similar statements (e.g. Deut. 8:2, 13:1–3). The only reason I can see as to why someone would insist that the testings were for the people, not God, is because they bring to the text a theology which will not allow them to accept the straightforward meaning of the text: God tests people to find out how they shall resolve their character.