What follows is an excerpt from my book The Evangelical and The Open Theist. This is the first of two posts specifically addressing divine foreknowledge.
Impassibility and immutability are not, however, the source of greatest controversy in this debate. Openness is so unsettling to classical systematicians because it threatens a foundational presupposition of traditional theology: exhaustive divine foreknowledge.
Philo argued that, since God foreknows all things that will ever transpire, certain actions of God as described in Scripture, such as divine repentance, are genuinely impossible. Indeed, a God capable of repentance, regret, surprise, and “if” and “might” statements simultaneously possessing exhaustive foreknowledge of all future events, including his own actions, seems logically incoherent.
Some, such as Tertullian, have chosen to accept these seemingly contradictory points. After all, only the “arrogant and the dogmatic find paradox hard to accept.” To the open theists, however, this is not a matter of paradox, comparable to Christ’s ability to be simultaneously fully God and fully man, but a matter of logical contradiction. To simultaneously possess foreknowledge and be uncertain about future events is a contradiction in terms, similar to a square circle. In light of the biblical witness and in search of a more coherent system of theological thought, open theology has challenged the traditional understanding of God’s foreknowledge and redefined it according to the biblical testimony.
(i) Denying omniscience?
Open theists often receive their most intense criticism over the doctrine of divine omniscience. Many critics of open theism charge that by denying God’s foreknowledge of all future events, open theists deny God’s omniscience. This, however, is an unfounded assertion. “Open theists affirm God’s omniscience as emphatically as anybody does. The issue is not whether God’s knowledge is perfect. It is. The issue is about the nature of the reality that God perfectly knows.” That is to say, the issue is not what God does or does not know; rather, the issue is what exists to be known.
The emotionally charged language of divine capability has clouded the real area of disagreement between open and traditional theologians: the ontological reality of future events as they exist in the present. Open and traditional theologians both affirm that God knows everything that is, and nothing can exist outside the knowledge of God. The two schools of thought part ways, however, over exactly what exists to be known.
Traditional theologians argue that the future is exhaustively settled, by either divine foreknowledge or divine determinism. In other words, the “‘definiteness’ of every event—the fact that it will occur this way and not any other way—eternally precedes the actual occurrence of the event.” Since God is omniscient and the future is a settled reality, then of course God possesses exhaustive foreknowledge of all future events.
Open theologians, however, contend with this understanding of the future. To them, the future consists of unsettled possibilities. Since God knows all of reality perfectly and Scripture seems to portray God as facing a partially open future, the future must indeed be partially open. Open theists argue that the future is a realm of possibilities—except where an omnipotent God has chosen to remove possibilities in favor of a settled reality or where present and past circumstances make future events inevitable—and God knows it as such. If God does not know for certain future free actions, for example, it is only because those future free actions do not yet exist to be known.
To the open theist, claiming God doesn’t know the future is the same as claiming God doesn’t know in what year George Washington landed on the moon. In this sense, to say that “God doesn’t know” is not a statement of divine ignorance but simply a testament to a reality that does not exist to be known. In disagreeing about God’s knowledge of future events, open and traditional theists “are disagreeing about the content of reality, not about the omniscience of God.” It is disingenuous to accuse open theists of denying God’s omniscience simply because they have a different understanding about the existing contents of reality.
Indeed, God exhaustively knows all contents of reality. When possibilities exist only as possibilities, God knows them as such, but when possibilities become knowable as actualities for the first time, at that moment, God knows them as such. In reality, divine foreknowledge is only a small aspect of a theological system based on understanding God’s relationship with his creation.
The open theist’s understanding of omniscience implies, of course, that God’s knowledge expands and changes as events unfold, demonstrating a real change in God in response to a real change in his creation. The foundation of open theism is the understanding that “God’s relationship to others in time and history is real and affects the very life of God.”
(ii) The futility of foreknowledge
The openness debate has sparked so much controversy because many see open theism as diminishing God’s glory, believing that a God who knows the future exhaustively is greater than a God who does not. Besides falling back into the trap of assuming that human beings are capable of determining what qualities perfection necessitates—exhaustive foreknowledge, for example—a priori, and then attributing those characteristics to God, this assumption is simply incorrect. In fact, by logical necessity, if God foreknew the future exhaustively, he would be unable to alter it.
Consider David Basinger’s example of Susan, a young woman who has received proposals of marriage from two different men and is seeking God’s guidance as she tries to decide which proposal to accept.
What sort of guidance might God choose to give her? God knows, of course, everything there is to know concerning the personality, temperament, physical condition and so on of each of the three persons involved, as well as their potential for future happiness under various conditions. He knows far more, then, than even the wisest and most skillful human marriage counselor. But what more would be added if we assume that God somehow “sees” the actual future? Suppose he looks into the future and sees Susan unhappily married to Tom. Could not God, on the basis of this, warn Susan that she had better accept Kenneth’s offer instead? A moment’s reflection will show this to be incoherent. What God knows is the actual future, the situation in which she actually is married to Tom. So it is nonsensical to suggest that God, knowing the actual future, could on the basis of this knowledge influence things so that this would not be the actual future, which would mean that God would not know Susan as being married to Tom…I trust the point is clear. In general, to assume that God does anything in the present on the basis of his knowledge of the actual future which could have an effect on that future immediately leads us into the philosophical morass of circular explanation and circular causation.
Foreknowledge of future events does nothing to add to God’s glory, but rather shows God—from the human perspective at least, which is the only perspective from which man can relate to him—helplessly anticipating all the horrors of world history from all eternity, or worse, predestining them. A God seeing the future in terms of possibilities, however, would be able to anticipate possible tragedies and intervene so that they don’t become actual tragedies. This is the model of God suggested by openness, and it is a model compatible with the biblical witness.
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 Sanders, “Historical Considerations,” 71.
 For a comprehensive defense of God’s ability to change his mind from the perspective of those adhering to the traditional understanding of divine foreknowledge see J. Daniel Hays’ “Anthropomorphism, Revelation, and the Nature of God in the Old Testament.”
 Boyd, God of the Possible, 16.
 As discussed below, this is still the issue even if God’s existence outside of time is conceded.
 Ibid., 16-17.
 Consider, for example, the title of Bruce Ware’s book, God’s Lesser Glory: The Diminished God of Open Theism.
 According to simple foreknowledge, God would be unable to alter the future because his foreknowledge of that future precludes the possibility of the existence of any other future. According to the Augustinian/Calvinist and middle knowledge model, God would be unable to alter the future because he has already predetermined it from eternity. Calvinism and Molinism (middle-knowledge) are able to escape the helplessness that the simple foreknowledge model throws upon God, but these two schools of thought run into their own problems in addressing biblical motifs discussed in the previous chapter. The God of Calvinism and Molinism has exhaustive foreknowledge of the future because he has determined all future events or manipulated all future events based on counterfactual, respectively. Simple foreknowledge teaches that God has exhaustive knowledge of future events, not because he determines them, but because he is able to gaze into the future. The merits of Calvinism and Molinism as opposed to openness is not relevant to the topic at hand. The drive of this book is not to demonstrate the superiority of open theology in comparison to other theological schools of thought, but rather demonstrate the compatibility of open theology with evangelical theology. Since these models are universally accepted as compatible with evangelicalism, they serve as a good comparison with open theism for the problem at hand. For a thorough discussion of the merits and drawbacks of all four schools of thought, see James K. Beilby and Paul R. Eddy, eds., Divine Foreknowledge: Four Views, (Downers Grove, IL: InterVarsity Press, 2001).
 Hasker, 149-50.