I recently read Greg Boyd’s explanation of Christ’s foretelling Judas’s betrayal and Peter’s denial. The basic issue is that in open theism, a free choice cannot be foreknown. Boyd states that at the time of their sins, Judas and Peter were not free (i.e. they couldn’t choose remain faithful to Christ). But since their prior free choices had formed their character, they were still responsible even if not free at that specific moment. (Boyd on Peter, Boyd on Judas)
While I suspect this explanation is unsound for multiple reasons, let’s for the moment grant that it’s true. What about cases were the future is foretold, yet counterfactual ability is asserted?
Matthew 26:52-54: But Jesus said to him, “Put your sword in its place, for all who take the sword will perish by the sword. Or do you think that I cannot now pray to My Father, and He will provide Me with more than twelve legions of angels? How then could the Scriptures be fulfilled, that it must happen thus?”
Christ claims the ability to do otherwise and that what He was going to do. Even if Judas and Peter didn’t have the ability to do otherwise, Christ did. So scripture asserts future free acts can be foreknown.
How does this singular example impact all of open theism? Scripture teaches God’s knowledge is infinite:
Great is our Lord, and of great power: his understanding is infinite. (Psalm 147:5)
So if future free choices are knowable, God knows them. Open theism relies on future free acts, as a category, being unknowable. One counterexample impacts the whole system.