Related to the post on recommended reading in apologetics from a few weeks ago, here are a few thoughts on the problem of evil. I think that this, in some form or another, is probably the objection that is most often raised by unbelievers in evangelical and apologetical conversations.
First, we must emphasize that the problem of evil is a real problem that must be dealt with by the Christian in giving a reason for the hope that is within them (1 Pet. 3:15) and in earnestly contending for the faith that has been delivered once for all to the saints (Jude 3-4). The problem of evil is raised as a charge that there is logical inconsistency in the Christian worldview. If Christianity is logical incoherent then there is not any amount of positive evidence that can be raised to save it. Internal inconsistency means that we would have no intellectual grounds for believing the Gospel. So we must answer this objection to show that Christianity is internally consistent.
This is the way that the problem is usually phrased as a syllogism:
1. God is completely good.
2. God is completely powerful.
3. Evil exists (or happens).
4. Therefore, God must not be completely good or completely powerful.
David Hume expresses the conclusion: “Is he willing to prevent evil, but not able? Then he is impotent. Is he able, but not willing? Then he is malevolent. Is he both able and willing? Whence then is evil?” (Dialogues Concerning Natural Religion, 88)
The first thing that we should note here is a presupposition, or an unargued assumption, on the part of the objector. The one who raises this objection assumes that evil exists, that is to say, he assumes that there is such a thing that can objectively be called evil. We will be brief here but it needs to be pointed out that the unbelieving worldview here presumes something that is impossible according to its own principles that deny God’s existence. In other words, without the first two premises being true there is no contradiction with the introduction of the third premise. So we ought to ask the unbeliever how they know that there is such a thing as evil. Common answers include that morality is derived from sense experience (empiricism or logical positivism) or that morality is culturally or personally subjective. I won’t go into this now but none of these answers allow for an absolute moral standard. So we must insist, in order for there to be a problem of evil the unbeliever must presuppose exactly what he seeks to deny. So the problem of evil shows an absolute internal inconsistency in all unbelieving worldviews.