This is the way I've grown to accept that God knows everything ... it is not a perfect explanation and I may be wrong - but it is a personal perspective which it seems he demonstrated for me. God gave me four special dreams. When I realized these were miraculous I began to ask God questions. Dream One: I had no child but in my dream I had a little girl. Pink dress, dark thick hair, and bright eyes. About two or three years old. I was sitting with my mother at a picknick table at my childhood home under a tree where I played as a child. My little girl was coming toward me and I held out my arms to welcome her, but she disintegrated right before my eyes. Never reached my arms. The end. Dream Two: At this time I lived in an apartment with my first husband and the laundry room was in the basement of the building. In the dream I was doing laundry along with my first husband and I was full of horrible emotions. Anger, hatred, fear, puzzlement, panic and deep sorrow. The end. Dream Three: Same apartment. Same husband. Same dream. Same feelings. Now, it was several years later after our marriage crumbled into divorce and for me a remarriage that I had Dream Four. It was this dream which finalized my dreams had to be a miracle. Everyone of them had fallen in place in order and were made clear. In the last dream I was sitting in the passenger seat of a Volkswagen automobile. That was a puzzle to me for I had only ridden in one a few times in my life so it wasn't significant to me. My first husband was in the driver's seat. Odd. He/we had never owned one. The parked auto was pointed toward the neighborhood street and was tilted upward at a particular angle. In the back seat was a woman I did not know. She handed me a small box and in it was a wedding band and I understood that something else came with it, but I did not know what it was. My husband did not say anything but just wrung the steering wheel and had a perturbed look on his face. The end. Now, here is how my eyes were finally opened: Some time later my second husband and I were looking at one of his family photo albums. He pointed out to me his first wife and said she loved Volkswagens and always drove one. I suddenly realized our home, which had been hers with him, had a sloped driveway which tilted upward toward the street! Then I knew the wedding band was hers to give to me and with it came her husband and her son!!! True, my first husband never did said anything about our getting back together even though he came once to visit me after our divorce. In marriage number one I did have a miscarriage while we were on a road trip out west. I believe now it was a daughter. When my first husband told me he wanted a divorce we washed clothes together that weekend and I did have all those horrible feelings. When I finally asked him to move out because he was determined to get the divorce - guess what. We washed clothes together that weekend and I had those awful feelings again. Then came this eye-opening fourth. I began to ask God questions: If you knew all these things were ahead of me, why didn't you tell me what to do? He answered! "I just wanted you to know I am real, I am alive, I KNOW what is going on in your life and I care." I've had to believe that my Lord is with me ever sense no matter what. He doesn't always change things but he is there. We do have freewill and there will be consequences to our decisions and life is a risk because we are mortals, but he still somehow KNOWS the future before it happens. Another way to look at his omniscience is that HE created us with a plan in mind. He set in motion the beginning and has established the end. He knows how things will turn out ... yet allowing us freewill in the meantime to make good or bad choices. I don't think he decides for us whether we will go to his kingdom but allows us individually to undo the choice Adam and Eve made. Then he chooses us. Even Cain had a free choice. God knew Cain had evil in his heart and warned him. Don't you know if you do well you will be accepted? Cain chose not to do well. What happened to him next was no surprise for God because God already had a plan in place. My best understanding of God's miracle. Sorry this is so long.
I think there are several serious problems with this, beginning with the assumption that these dreams were miraculous in the first place.
You have had a series of dreams and, after later events occurred, interpreted those events as the fulfillment of the dreams. From there you concluded that the dreams came from God, and from that conclusion you inferred a particular doctrine of divine foreknowledge. But saying it doesn't make it so. Every step in that chain requires an argument. None of it is established merely by telling the story.
Further, your take away from these dreams is proof that they cannot have been from God. If God communicates something, He is perfectly capable of communicating what He intends to communicate, but you are here to attribute to God a revelation so unclear that the person receiving it walks away convinced that God has demonstrated something about His nature that isn't true. God gives better revelation than that.
And there are perfectly ordinary (i.e. non-doctrinal) reasons to be cautious about interpreting dreams this way. Human beings dream constantly. Most dreams are forgotten. Some are remembered because later events give them apparent significance, and our memories and interpretations of them are then filtered through everything that happened afterward. That doesn't mean you're being dishonest. It just means that you're human. The fact that a later event reminds us strongly of an earlier dream does not establish that God supernaturally revealed the event beforehand.
Your fourth dream illustrates the problem especially well. You describe it as the dream that finally convinced you the others were miraculous, yet you say it occurred years after your first marriage ended and after you had remarried. Your second husband's former wife had already existed. Her preference for Volkswagens already existed. Your husband and his son already existed. The house and its sloped driveway already existed. Those were not future facts God would have needed foreknowledge to know. They were merely facts that
you didn't know. Even if we somehow established, if we simply grant for the sake of argument, that God supplied that information to you supernaturally, it would demonstrate God's knowledge of existing facts, not exhaustive foreknowledge of future free choices.
The miscarriage interpretation is even less compelling. You dreamed of a little girl who disappeared before reaching you, later suffered a miscarriage, and now say, "I believe now it was a daughter." But you don't know that. You are interpreting the earlier dream in light of what happened afterward. Again, perhaps the interpretation is meaningful to you, but personal significance is not evidence sufficient to establish a doctrine about the nature of God's knowledge.
Even if, purely for the sake of argument, I granted that one of the earlier dreams contained genuine knowledge of a future event, exhaustive definite foreknowledge still wouldn't follow. Open Theism has never claimed that God knows nothing about the future. God knows everything He has determined to do, everything He has determined will certainly happen, every present fact, every intention, every possibility, every possible consequence, and anything about the future that is presently knowable. The issue is whether future free choices already exist as settled facts to be known.
Knowing one future event therefore no more establishes exhaustive definite foreknowledge than my knowing that the sun will rise tomorrow establishes that I know what you will eat for breakfast next Tuesday.
You also say that God "knows how things will turn out" while nevertheless allowing us free will. But that isn't an explanation of the problem. It is merely a restatement of the two propositions whose compatibility is in dispute.
If God has eternally and infallibly known that tomorrow I will choose A, can I choose B instead?
If yes, then God's knowledge can be mistaken.
If no, then B isn't actually possible.
Simply saying that I "freely" choose A does nothing to answer that problem. The question is whether I genuinely could have chosen otherwise.
And then you bring up Cain, which I find particularly interesting because Cain is a remarkably poor example for your position. God confronts Cain before the murder and tells him:
"If you do well, will you not be accepted? And if you do not do well..."
God warns him that sin is crouching at the door and tells him that he must master it.
You say, "Cain chose not to do well."
Exactly.
But if God already possessed Cain's murder of Abel as an eternally settled and infallibly known fact, then Cain could not do well. Cain could not heed God's warning because doing so would falsify God's eternal knowledge. The text presents alternatives as genuine while your doctrine requires one of those alternatives to have been impossible.
Nor does saying that "God already had a plan in place" solve anything. Of course He had a plan in place. Having a plan is not the same thing as knowing only one possible future exists.
God can say, "If you do this, I will respond this way, and if you do that, I will respond that way." Scripture is filled with precisely that sort of language. An infinitely wise God does not need every decision any person makes eternally frozen into place in order to know exactly how He will respond to whatever His creatures actually choose.
Likewise, God establishing the ultimate end of history does not require Him to settle every event leading to that end. If God determines that something will happen, then it will happen. His ability to accomplish His purposes does not depend upon every human decision having already existed eternally as a settled fact.
So I don't think these dreams provide a basis for the doctrine you're drawing from them. More importantly, I wouldn't begin with the assumption that they were messages from God and then use them to determine what God's nature must be.
That's backward. Claims of revelation have to be tested against what is true about God, not used as personal trump cards from which doctrines about God are constructed.
Your experiences may have been powerful and meaningful to you. I don't question that. What I question is the leap from "I had dreams that later seemed to correspond to events in my life" to "God miraculously gave me these dreams in order to demonstrate that He exhaustively knows a settled future." That's not an explanation of the dreams, but an interpretation of them.