Apologetics should be both offensive and defensive. We give answers to non-Christians, and we challenge them with questions to help them see the inconsistency of their position. Remember that Proverbs 26:4-5 teaches that we should sometimes avoid answering a fool “according to his folly,” so that we do not become like him (that is, we should defend the gospel on its own terms and not give in to non-Christian presuppositions), and at other times we should “answer a fool according to his folly, or he will be wise in his own eyes” (that is, we should take an offensive approach to apologetics, showing the non-Christian the error of his own thinking by carrying it out to its contradictory consequences). The non-Christian is confused . . . and he denies things he knows are true, just as the prodigal son was probably doing.
As we defend the Christian faith, we can ask non-Christians why they believe what they believe. When they explain why, saying, for example, that it is logical, we can ask why they trust logic. We can keep pushing them to their final answer. This is not a game. We need to do this with much love and respect. Otherwise, we will lose the opportunity to explain the gospel. But if we continue asking until there are no more questions, where does the non-Christian end up? What is his “final answer?” He will have to back up to something beyond which he has nothing more to say.
One way or another, that final answer for the non-Christian will be reduced to the fact that he believes it simply because he thinks it’s true. He may say something like, “I believe it because it just seems true to me,” or “I believe it, period,” or “I believe it because I want to.” In any case, the non-Christian essentially makes himself the judge of what is true and false and right and wrong.
This eliminates all certainty for the non-Christian, because to be sure of anything, he needs to know everything. It also eliminates consistency, because he knows deep down that he is not God and that he cannot simply decide for himself what the truth is.
The Christian alternative is to accept God as the judge and source of truth. . . . As a Christian, I cannot back up any further than God himself; I cannot elevate something above him. If I appeal to an authority superior to God, I have just contradicted my own worldview and destroyed the foundation underneath me.
-Richard Ramsay, The Certainty of the Faith, p. 149-150