By default, an acceptance of Open Theology requires the believer to accept a concept of time where the future does not yet exist. This means that “open theists must reject the view of time that is held by the majority of physicists and that held by many philosophers of time, namely, the B-theory (also “static” or “tenseless” time)” (Cuthbertson, 2005, p. 78). This theory of time holds that there is “no ontological difference between the past, present, and future [and] that the temporal change we all experience is relegated to a psychological anomaly” (Cuthbertson, 2005, p. 78). The B-theory of time stands opposed to the A-theory, which posits that temporal changes are real, and Presentism that suggests the past has ceased to exist and the future has yet to exist – leaving only the present (Cuthbertson, 2005, p. 78).
At the present time there may be no way of knowing which of these theories of time is the most accurate, however, I would suggest that the B-theory of time seems the most Biblical. Consider this, as temporal beings mankind can only remember the past, experience the present, and anticipate the future. God, however, is atemporal as He exists outside the boundaries of time. It is hard for temporal beings to imagine, but the Bible declares that God fills Heaven and earth (Jeremiah 23:24). God is omnipresent. He is everywhere. If the B-theory of time is correct, this means that God exists in the past, present, and future alike with no respect to the passage of time. This would explain how God can boldly exclaim how His plans will unfold in the future. It is a vision of God that is both Biblical and awesome in power. Open Theology’s vision of God simply does not account for His work in the past, present, and future.
Source
Cuthbertson, M. R. (2005). Time, the “open acquittal,” and divine omniscience: Two internal problems with open theism. Westminster Theological Journal, 67, 75-83.