Keller addresses another common objection to Christianity, namely the question of how evil could exist in a world ruled by a God who is both all-good and all-powerful. Against the apparent force of this objection, Keller responds by saying that many philosophers no longer accept its validity and, further, that the existence of evil and suffering actually helps to prove the existence of God.

One fallacy inherent in the objection is that it assumes that everything defined as “evil” must either be pointless or contrary to the purposes of a good God, but this is by no means an easy thing to establish: “Just because you can’t see or imagine a good reason why God might allow something to happen doesn’t mean there can’t be one” (23). Keller invites his readers to consider some of the suffering in their own lives, believing that they will acknowledge that, at least in some cases, the perspective of time and growth has enabled them to see the possibility of there being a reason for that pain. If that is so, he argues, then why would it be impossible to imagine that an infinite God might allow all the kinds of suffering we see and do it for purposes that are not yet apparent to us?