We wish to show that every individual event which occurs in God's creation is willfully caused by God, where we understand God to be the omnipotent and omniscient creator of the whole universe, i.e. the creator of everything that exists outside of God.
Consider first the case where God is in control of himself, and let E be an event that occurs. Then E is part of a (possibly trivial) causal chain with a set of (uncaused) root causes. Suppose towards a contradiction that there is some root cause F which is not part of God's will. It cannot be that F is a part of God, because that would mean God caused an event without willing it, violating his control over himself. So F is outside God, which means it is part of God's creation. By omnipotence, God could have created a world W' which is identical to the actual world W in every respect except that F is not an element in W'. Since God is omniscient and in control of himself, then he willfully created W instead of W'. Since the only difference between W and W' is the occurrence of F, then God willfully caused F, contradicting the definition of F as a root (uncaused) cause. So all root causes of E are part of God's will, which by transitivity of causation means God causes E to occur. So every root cause of every event is a part of God's will. Furthermore, by omniscience, if God wills the beginnings of a causal lattice then he wills every event therein. We conclude that if God is in control of himself, then God willfully causes every event to occur.
Next consider the case where God is not in control of himself, but where God's creative acts are always deliberate, i.e. an exercise of his will. Let H be an element of God which God does not control. If H causes some event E, then that event is either involved with God's creation or it is not. If it is involved with God's creation, then God considered in his decision of what to create this action of H on his creation. By omnipotence, he could have created a world W', identical to the world W which he actually did create in every respect except that H does not act on W' to bring about E. Since God's act of creation is deliberate, that means he wills the existence of W as opposed to W'. Since the only difference between W and W' is the occurrence of E, then it follows that God wills E, and moreover causes E to occur by creating W when he could have created W'. If on the other hand E is not involved with God's creation, then since all that exists outside God is God's creation, then E must be an event within God. Consider the last element E' of a causal chain beginning with E and not containing any event involved with God's creation. Then either E' is causally inert, or else the same argument applied to H can be applied to E' to show that whatever event involved with creation which is caused by E' is willfully caused by God. So any elements which are not willed by God are bound up within God, i.e. are independent of creation. Thus any element only ever acts on creation by the will of God.
We are left with the case where God's creation is not entirely deliberate. We claim that this case is impossible. For consider a (causally) first nondeliberate creation N of God. There are two senses in which N could be nondeliberate. On one hand, N could be nondeliberate in the sense that there is some other object N' which is different from N, and whose creation would satisfy God's will no better or worse than that of N. Let E be the event that God caused the creation of N (as opposed to N'), and let F be a root cause in the causal chain leading to E. Then since E (causally) precedes any nondeliberate creative act the previous arguments apply to show that E is caused by God's will. Thus God wills the creation of N over the creation of N', which contradicts the definition of N' as not willed by God over N. Alternatively, N could be nondeliberate in the sense that God did not intend to create N at all. Yet in that case the previous argument again applies, leading to another contradiction. Thus the hypothesis of a nondeliberate creation always leads to a contradiction. We conclude that God's creation is in fact deliberate, and therefore that every individual event which occurs in God's creation is willfully caused by God.