So here's the deal: Can God be both passionate and impassible (not subject to change in emotion)? Can we rest in the assurance that God has passionate gracious love for his people, for his creation, and that he cares for us immensely and personally--and yet hold that God does not actually change in his emotional state? For Weinandy, this is the mystery of the biblical God; pushing into this mystery is the only way to explicate the God of the Bible.
This makes a great deal of sense. Many Christians want to be able to believe, on the one hand, that God cares deeply for his creation and for his people. He is not distant or removed from our suffering. And yet, can a suffering God really help? Do we relate more effectively to a God who suffers, or to a God whose mysterious, paradoxical relation between transcendence and immanence, suggests that, while he is infinitely near to us, he is also wholly other.
The question of God's impassibility, passibility, and the possibility of his suffering cannot escape a discussion of the so-called relation between the ontological and economic Trinity. Traditionally, the economic Trinity has been posited as that which can be known by us mere mortals. God as he reveals himself to us in history (and Scripture). The God, that is, of Father, Son and Jesus Christ in their transfiguring revealedness. The ontological Trinity, on the other hand, is God as he exists in himself (The Existent One), and in his essence. This God we cannot really speak about. To paraphrase John of Damascus, we might be able to know this God (relationaly) but we can't talk about what we know of this God. To bifurcate between the ontological and the immanent Trinity in stark terms is to use the unity of God; we end up, not with three persons, but with six! Three we can talk about, three we can't. Well, this is just odd.
The solution to the question of whether God suffers cannot rely on this distinction (economic/ontological). As Rahner put it, the ontological Trinity is the economic Trinity! It is better to say of the Godhead, both that he is unchangeable, immovable, and always faithful to who he is (which includes faithfulness, passion, love, etc.), but that he does not change, in passionate fits and starts, like you and I. Rather, he always is passionate, gracious, kind, loving...but this is not to say he is distant, predictable and mechanistic.
I'm beginning to appreciate Weinandy's critique of the modern emphasis on the passibility of God. Many questions remain and many implications are left to draw out and nuance, but it's a good beginning.