An atheist once told me that the Christian God is more complex than extreme complexity seen in creation -- and hence infinitely improbable. How should I respond to him? -- Edwin

It is a false comparison. You cannot compare a spiritual (immaterial) being to the physical creation. The physical creation requires a creator because it has not been around for infinite time, and could never have formed on its own. (We know this because of the Big Bang; the universe came into existence some 14-15 billion years ago, by the latest reckoning.) Further, the laws of physics say that everything that has come into being requires a cause. God, on the other hand, is timeless, and has never come into being; he requires no creator, since he is the creator. Good question!