Several posters here seem to me to ignore an important presupposition of classical Arminian theology and of open theism. (I could probably list some other theologies that also affirm God’s self-limitation, but our discussion has been mostly about these.) That presupposition is that, in creation, as in incarnation (with important differences) God limits himself.
All Calvinists that I know affirm some kind of divine self-limitation, although they are much less likely to promote it as a crucial theological idea than, say, open theists. I argue that it functions as a “control datum” for classical Arminians, as well. (Reformed scholar Richard Mueller has found this through his own archeology of Arminius’ theological influences and ideas.)
The reason God is not the author of sin and evil is that he limits his power in relation to creation. By his own choice he is not, in the inimitable words of Baptist theologian E. Frank Tupper, a “do anything, anytime, anywhere kind of God.” He COULD be because he is omnipotent, but he chooses not to be that kind of God.
Why? For the sake of having real, rather than imaginary, relations with human persons. (Perhaps also for the sake of having such relations with other kinds of persons, but we know little of that.) We all believe that, in some way or other, God limited himself in the incarnation. (Whether you are a kenoticist or not you have to believe in some kind of divine self-limitation in the incarnation. Kenoticists just take it farther than, say, two minds or two consciousnesses Christologists.) For example, he could not do miracles in certain times and places due to people’s lack of faith.
The idea of the “openness of God” to new experiences and to grief, etc., was proposed and promoted by Barthian theologian Thomas Torrance in Space, Time and Incarnation. It was actually he, rather than Pinnock or any other open theist, who coined the phrase “openness of God.” (See pp. 74-75 for the entire statement about God’s entering into time with us.) Other non-open theist theologians who espouse a view of God limiting himself in relation to creation are Dallas Willard (see The Divine Conspiracy, pp. 245ff) and the previously mentioned E. Frank Tupper (see A Scandalous Providence: The Jesus Story of the Compassion of God, passim.)
Why do these and many other theologians posit God’s self-limitation in relation to creation? To make coherent belief in genuine personal relationships between God and persons and to avoid divine determinism which inevitably makes God the author of sin and evil.
We don’t have to know all the “ins” and “outs” of God’s self-limitations to believe that he does limit himself and that his self-limitation is the reason for evil in the world. That is, it is the indirect reason but not, of course, the effectual cause. God allows evil without foreordaining it or rendering it certain. Why does he intervene to prevent or stop it sometimes and not other times? Well, we have no way of knowing that anymore than we can know why Jesus could sometimes do miracles and other times could not. The reasons are hidden in God; he has not seen fit to tell us what they are. We know faith sometimes plays a role. Sometimes obedience does. But we can’t know all the reasons.
I, for one, would rather believe God limits his power than believe that God’s power is the ulterior reason for whatever is happening.
For a powerful refutation of meticulous providence see theologian David Bentley Hart’s little book The Doors of the Sea: Where Was God in the Tsunami? (Eerdmans, 2005) It’s a powerful critique of any theology that attributes all calamaties to God’s providence. Hart doesn’t quote this adage (paraphrased), but his book is consistent with it: “Nobody should articulate a theology that cannot be spoken standing in front of burning children.” Hart warns against any theology (such as he sees in consistent Calvinism) that makes God (however inadvertently) “morally loathsome.” “[i]f indeed there were a God whose true nature–whose justice and sovereignty–were revealed in the death of a child or the dereliction of a soul or a predestined hell, then it would be no great transgression to think of him as a kind of malevolent or contemptible demiurge, and to hate him, and to deny him worship, and to seek a better God than he.”
The only way to avoid that (logically, in my opinion) is to affirm God’s voluntary self-limitations in relation to creation.
Fortunately, most divine determinists (including most Calvinists and many Lutherans) DO NOT go so far as to attribute sin and evil to God. In fact, most strongly deny that God is the author of sin and evil. The point is, however, that logical consistency would seem to require that within their systems. And we all know someone who has taken it that far.
Calvinists often say that Armianians “can be” Christians by virtue of a “felicitous inconsistency.” Well, I will say the same about Calvinists at this point. Their theology requires, as a “good and necessary consequence,” that God be the author of sin and evil. That they deny he is the author of sin and evil is a felicitous inconsistency. I applaud them for not following the logic of their doctrines of providence and predestination to their natural conclusions. However, I worry that many of the “young, restless, Reformed” people will carry it that far. I have seen it done.