You guys might like looking into the overviews of the existentialists. Kierkegaard and Barth are my favorites, but best to stick to summaries than dig through all of the verbose writings of these two.
Keep in mind that, though God is omniscient, we have examples of him changing his mind throughout the Bible.
I think an example here is the story of Ahab. 1 Kings 21.
He was a king, Jezebel was his queen.
He wanted Naboth's vineyard, but Naboth didn't want to sell his vineyard to Ahab. When Jezebel learns of this, she frames Naboth for blasphemy, and has Naboth stoned to death, and encourages Ahab to go and take the vineyard.
While Ahab is taking possession of the vineyard, Elisha tells Ahab that he will die in the vineyard, and his blood will be licked up by dogs there, and wipe out all of Ahab's decendants.
Ahab was very sorry, put on sackcloth, repented.
God tells Elisha, hey, look Ahab repented. Because of that, God changed his mind, and told Elisha that the destruction of Ahab's family wouldn't happen in his lifetime, and that the prophecy of him dying at the same place Naboth was stoned did not come to fruition.
Did God lie to Ahab? No. IMO, God told Ahab what was going to happen, and had every intention on fulfilling his promise. But, Ahab had free will, and Ahab chose to repent. So, God changed his mind, and tricked him into dying in battle on a future date.
There are many other examples. Jonah and Nineveh, Naoh and the flood, Moses interceding for Israel, among others.
These are stories of God making a prophesy, which he obviously knows will pass, and then changes his mind about the prophesy based on the repentance of sin. I don't see how you can see all of these examples and come to the conclusion that salvation for us is completely different, where God made up our minds for us on whether or not we will accept salvation. I just doesn't compute for me. I guess you could weasel it in there that God knew he was going to change his prophesy, and that is why he gave it, but that just doesn't seem to read into the character that we are reading about in these stories.
So, no, I do think that we have the ability to accept or reject God's grace. It assumes that there is some amount of chaos in the world, and that "everything happens for a reason" is not necessarily true. The fact that free will and omnipotence both exist is a great mystery, and something a temporal, finite human mind can really understand. Soren Kierkegaard described this as the "qualitative infinite difference" between God and man. God is not bound by time, or 4 dimensions, and is not limited quantitatively. He is perfectly God, so can be perfectly qualitative, and still be right. The failure of us being able to wrap our brains around that is a biological failure of our capabilities, not some paradox than can't be true.
