Many Christians do not share their faith with unbelievers simply out of fear. They’re afraid that the non-Christian will ask them a question or raise an objection that they can’t answer. And so they choose to remain silent and thus hide their light under a bushel, in disobedience to Christ’s command. Apologetics training is a tremendous boost to evangelism, for nothing inspires confidence and boldness more than knowing that one has good reasons for what one believes and good answers to the typical questions and objections that the unbeliever may raise. Sound training in apologetics is one of the keys to fearless evangelism. In this and many other ways apologetics helps to build up the body of Christ by strengthening individual believers.
Now this dismissive attitude toward apologetics’ role in evangelism is certainly not the biblical view. As one reads the Acts of the Apostles, it’s evident that it was the apostles’ standard procedure to argue for the truth of the Christian worldview, both with Jews and pagans (e.g., Acts 17:2–3, 17; 19:8; 28:23–24). In dealing with Jewish audiences, the apostles appealed to fulfilled prophecy, Jesus’ miracles, and especially Jesus’ resurrection as evidence that he was the Messiah (Acts 2:22–32). When they confronted Gentile audiences who did not accept Jewish Scripture, the apostles appealed to God’s handiwork in nature as evidence of the existence of the Creator (Acts 14:17). Then appeal was made to the eyewitness testimony to the resurrection of Jesus to show specifically that God had revealed himself in Jesus Christ (Acts 17:30–31; 1 Cor. 15:3–8). Frankly, I can’t help but suspect that those who regard apologetics as futile in evangelism just don’t do enough evangelism. I suspect that they’ve tried using apologetic arguments on occasion and found that the unbeliever remained unconvinced. They then draw a general conclusion that apologetics is ineffective in evangelism.
-William Lane Craig in Reasonable Faith: Christian Truth and Apologetics, Kindle Edition, 290-295, 298-306