"When our ancestors referred to pains and sorrows as God's 'vengeance' upon sin they were not necessarily attributing evil passions to God; they may have been recognising the good element in the idea of retribution. Until the evil man finds evil unmistakably present in his existence, in the form of pain, he is enclosed in illusion. Once pain has roused him, he knows that he is in some way or other 'up against' the real universe: he either rebels (with the possibility of a clearer issue and deeper repentance at some later stage) or else makes some attempt at an adjustment, which, if pursued, will lead him to religion. It is true that neither effect is so certain now as it was in ages when the existence of God (or even of the gods) was more widely known, but even in our own days we see it operating. Even atheists rebel and express, like Hardy and Housman, their rage against God although (or because) He does not, in their view, exist: and other atheists, like Mr Huxley, are driven by suffering to raise the whole problem of existence and to find some way of coming to terms with it which, if not Christian, is almost infinitely superior to fatuous contentment with a profane life. No doubt Pain as God's megaphone is a terrible instrument; it may lead to final and unrepented rebellion. But it gives the only opportunity the bad man can have for amendment. It removes the veil; it plants the flag of truth within the fortress of a rebel soul.
"If the first and lowest operation of pain shatters the illusion that all is well, the second shatters the illusion that what we have, whether good or bad in itself, is our own and enough for us. Everyone has noticed how hard it is to turn our thoughts to God when everything is going well with us. We 'have all we want' is a terrible saying when 'all' does not include God. We find God an interruption. As St Augustine says somewhere, 'God wants to give us something, but cannot, because our hands are full—there's nowhere for Him to put it.' Or as a friend of mine said, 'We regard God as an airman regards his parachute; it's there for emergencies but he hopes he'll never have to use it.' Now God, who has made us, knows what we are and that our happiness lies in Him. Yet we will not seek it in Him as long as He leaves us any other resort where it can even plausibly be looked for. While what we call 'our own life' remains agreeable we will not surrender it to Him. What then can God do in our interests but make 'our own life' less agreeable to us, and take away the plausible source of false happiness? It is just here, where God's providence seems at first to be most cruel, that the Divine humility, the stooping down of the Highest, most deserves praise."
* C.S. Lewis, The Problem of Pain, 93-94.