This is precisely what occurred on the day of Pentecost. As the apostle Peter preached God's Word and his hearers came under deep conviction, suddenly, they "were pierced to the heart" (Acts 2:37). This word "pierced" (katanusso) means, literally, "stabbed to the heart"11 like a sharp knife thrust into one's chest. John Stott notes that those who heard Peter were "cut to the heart, that is, convicted of sin and conscience-stricken."12 Only the Word could do this. Thus, Simon Kistemaker rightly concludes, "Their hearts were pierced by guilt so that they became deeply troubled."13 This is what occurs when the Word is preached in the power of the Holy Spirit. The Bible produces a sharp pain to the soul, a deep remorse over sin, necessary for salvation.

Facing the hardness of men's hearts in his day, John Calvin wrote, "There is nothing so hard or strong in a man, nothing so hidden, that the powerful Word cannot pervade."14 Unlike the superficial, synthetic messages of this age, God's Word is able to cut to the core of a person, leaving him flayed, exposed, and convicted. The Holy Scripture is the most powerful cutting instrument known to the preacher, the only scalpel that is able to penetrate human hearts, convict of sin, and expose human depravity. If Scripture is so powerful, being able to reveal one's sin and true need for Christ, why preach anything else?

Power to Convert

Beyond having the power to convict, the Bible also possesses the power to convert. The apostle Peter wrote, "For you have been born again not of seed which is perishable but imperishable, that is, through the living and abiding word of God" (1 Pet. 1:23). Just as a seed contains the germ and energy of life, so does God's Word. It is through this living Word that we are born again and made alive spiritually.

The imperishable seed, God's Word, contains the principle of new life within it and is able to generate spiritual life in the dead souls of men. In fact, Paul actually calls it the "word of life" (Phil. 2:16). By the working of God's Spirit, the Word alone can engender faith in the human heart (Rom. 10:17). The preacher's emotional appeals, colorful illustrations, and captivating stories may stir the emotions, but they cannot create life in the human heart. There can be no true, saving faith in Christ until His life-giving Word is sown into a heart sovereignly tilled and made fertile by the Spirit. Only then will the Word of God germinate and bring forth new life.

This is precisely what occurred on the day of Pentecost. The apostle Peter preached the Word of God, directly citing Joel 2:28-32, Psalm 16:8-11, 132:11, 2 Samuel 17:12, Psalm 89:3, and Psalm 110:1, and a great harvest of souls resulted. The Bible says, "Those who received his word were baptized; and there were added that day about three thousand souls" (Acts 2:41). Throughout the book of Acts, as the Word was preached, God was pleased to convert souls (Acts 2:27; 4:4; 5:42-6:1; 6:7; 11:21-22; 12:24; 13:46-49; 14:21; 16:14; 17:10-12; 18:8; 19:20).