According to theism there is a God who has, for example, the most understanding that anyone could possibly have. Open theism is the thesis that God’s future is to some extent open. It is not that God exists within time, but that time—or rather, changeability—is another of God’s attributes. The temporal dimension is certainly implicit in much of our ordinary talk of ordinary things (changeable continuants), but it is only our imperfect, quasi-spatial reification of change. Changeability itself originates with God’s power to change (e.g. to choose to create contingent continuants like us) should he wish to. The following shows that changeability is indeed a power, rather than a liability.
......It is one of several arguments I produced in response to Mawson’s recent argument that, since a temporal God would not know all about the future, if we had free will, whereas a timeless God would, and since God is maximally knowledgeable, so God is timeless. It is based on the observation that if God could be timeless—if a timeless divinity could create a world of people like us, while being above and beyond our personal and physical temporalities (or ways of being changeable)—then surely an everlasting (or Open theistic) God could have created such a world in a single moment of his relatively transcendental time. He would just have been creating things whose temporalities differed that much from his own, just as a timeless divinity would have been doing.
......Now, there are lots of possible worlds, which God would know all about even if he did not actually create all of them. Not creating some of them would hardly be a failure of omnipotence, as being unable to create them would. So suppose that God is everlasting and that he has chosen not to instantaneously create such a world as ours would be were God timeless, but has instead made it as Open theists believe it is. If God was timeless he could not do that, because he would have to know all about the future of any world that he could possibly create. So an everlasting God knows about (and is able to create) all the possible worlds of a timeless God, and more besides.
......God being maximally knowledgeable (and maximally powerful), we should be Open theists, at least according to Mawson’s methodology (and given the validity of such possible-worlds-talk).
......It is perhaps more clear that we should not conclude that God is timeless just because he could then be completely knowledgeable (and powerful) in respect of ourselves. That is because 100% of a little could be much less than 1% of a lot. To see that even more clearly, let RoboGod be an infinite computer that can create arbitrarily complex virtual beings, about which it would know (insofar as computers can know) everything, and over which it would have complete control. One might think that one might be such a creature (e.g. because Functionalism is conceivable) but even so, RoboGod might not know as much as (and is clearly less powerful than) someone who could create such a computer in the first place.