“And when they had appointed him a day, there came many to him into his lodging; to whom he expounded and testified the kingdom of God, persuading them concerning Jesus, both out of the law of Moses, and out of the prophets, from morning till evening” (Acts 28:23).
Notice that Paul used both prophecy and the Law of Moses in his evangelism. Prophecy appeals to a man’s intellect and creates faith in the Word of God. As he realizes that the Bible is no ordinary book—that it contains numerous indisputable prophecies that prove its supernatural origin—he begins to give Scripture credibility. However, the Law of Moses appeals to a man’s conscience and brings conviction of sin. A “decision” for Jesus purely in the realm of the intellect— with no biblical knowledge of sin, which comes only by the Law (Romans 7:7)—will almost certainly produce a false convert.