Consider the following passage:
He then said to me: "Son of man, go now to the house of Israel and speak my words to them. You are not being sent to a people of obscure speech and difficult language, but to the house of Israel -- not to many peoples of obscure speech and difficult language, whose words you cannot understand. Surely if I had sent you to them, they would have listened to you. But the house of Israel is not willing to listen to you because they are not willing to listen to me, for the whole house of Israel is hardened and obstinate. But I will make you as unyielding and hardened as they are. I will make your forehead like the hardest stone, harder than flint. Do not be afraid of them or terrified by them, though they are a rebellious house." [Ezekiel 2:4-9, NIV]
When I read through the book of Ezekiel a little while back, several things struck me about this passage:
1. God seems to indicate that Ezekiel's message would have received a better response if he'd been preaching it to people who didn't even understand the words he was saying. That's a pretty serious hardening of the heart, if anyone who doesn't even understand the message being said will give a better response than Israel would.
2. It seems like an interesting example of God's knowledge of what people would do in some non-actual scenario. Jesus says something similar about how Sodom and Gomorrah would have responded had they seen the miracles Jesus performed. In both cases it's a strong statement against God's people's unwillingness to believe. In both cases, if it's meant literally (rather than sarcastic exaggeration), it's an example of God knowing how people would respond if things had been different, indeed of something pretty unexpected that God seems to be saying would have happened if things were otherwise.
3. There's such a clear statement of Israel's unwillingness to listen to God. It doesn't say afterward that they didn't believe. It doesn't say simultaneously that they aren't believing but might. It says before he's preached anything that they are not willing to listen. The kind of hardening that's true of them is not the sort where it's unclear what will result. God is telling Ezekiel now that they're not going to respond favorably and not to fear. This does seem to suggest a pretty strong view of God's understanding of how people will respond to something.
4. There's still an acknowledgment that some will listen. Earlier in 2:7, and later in 3:11, God tells Ezekiel that his task is the same whether they listen or not. It doesn't say that some will nonetheless listen, even if most don't. It doesn't say that there's a chance they might listen, and God doesn't know for sure. This would have been a perfect opportunity to say either. What is says is to preach the message regardless of their response. Their response is irrelevant to whether Ezekiel preaches. I have a feeling open theists would want to read this statement as leaving the wiggle room they need for there being no guarantee of God's prediction being true. But I don't see that. I see God saying that they won't believe and that Ezekiel should preach no matter how they respond, not saying that anyone might or will respond favorably.