What God was doing before he created the world?

The dependence of creation upon God is also stressed in Augustine's treatment of time. (His most sustained and interesting treatment is in Book XI of The Confessions. ) The Manichaeans claimed that the doctrine of creation from nothing contains no sufficient explanation of why God should create at any given moment rather than any other and that it further poses the unanswerable question of what God was doing before he created the world. Augustine rebuts such objections by insisting that they rest upon a mistaken assimilation of time to an event in time. Creation from nothing entails that time too is a creature, which came into being with other things created. Thus the notion of events before the beginning of time becomes meaningless.

It's an old, old problem.