I'll just go ahead and cut to the chase. You will, rightly, affirm that God is omniscient. But your argument that foreknowledge or determinism would seem to invalidate God's virtue of longsuffering toward us, would also invalidate His expressed anger toward the disobedient.
Paul anticipated your objection when he said, Thou wilt say then unto me, Why doth he yet find fault? For who hath resisted his will? Ultimately that's what every argument against Calvinism boils down to.
Baptizo wilt say unto me, What reason doth he yet to have longsuffering? For who hath resisted his will?
The answer to that is easy, because Paul answered it for us. Now, you may not find that answer satisfying, and if not, then your issue is with the Spirit, and not with Calvinists, and you may have to re-evaluate the premises you're arguing from.