The chief and primary means by which the Holy Spirit communicates the grace of God to us is the preaching of the gospel. It is by preaching, first of all, that He creates faith within us. As Paul says, "Faith comes from hearing, and hearing through the word of Christ" (Rom. 10:17). The "word of Christ," which is the preached word of the gospel, is the means through which the Holy Spirit gives faith to faithless sinners. But do not think preaching is only for unbelievers. It is also the means whereby the Lord gives His people faith that they might continually trust Him and His promises. This is why we call preaching the primary means of grace.
The Belgic Confession says the Holy Spirit "kindleth" faith in us (Art. 22), and that it is "wrought in man by the hearing of the Word of God and the operation of the Holy Ghost" (Art. 24). When the powerful Holy Spirit accompanies the preached gospel, He gives new life and faith to those who hear. The Canons of Dort speak of the preaching of the gospel, saying, "What, therefore, neither the light of nature nor the law could do, that God performs by the operation of His Holy Spirit through the word or ministry of reconciliation" (3/4.6). In other words, preaching does what neither our own abilities nor even the law of God can do. The Spirit's work through preaching is explained in more detail when the Canons go on to speak of His power and internal work within us:
… he not only causes the gospel to be externally preached to them, and powerfully illuminates their minds by His Holy Spirit, that they may rightly understand and discern the things of the Spirit of God, but by the efficacy of the same regenerating Spirit he pervades the inmost recesses of the man; he opens the closed and softens the hardened heart, and circumcises that which was uncircumcised; infuses new qualities into the will, which, though heretofore dead, he quickens; from being evil, disobedient, and refractory, he renders it good, obedient, and pliable; actuates and strengthens it, that like a good tree, it may bring forth the fruits of good actions. (3/4.11)
All of this tells us that in the preaching ministry of any church, Jesus Christ must be the subject matter, from the beginning of the Bible in Genesis to its end in Revelation. Why would I say this? Simply put, not only did Jesus teach His disciples that all the Old Testament Scriptures were about Him (Luke 24:25-27, 44-47; John 5:39), but the apostle Paul spoke of his own preaching ministry among the Corinthians, saying, "we preach Christ crucified" (1 Cor. 1:23).
Another vital aspect of biblical preaching is that we know that not all who sit and hear the good news about Jesus proclaimed actually believe it. As Jesus taught in the parable of the sower (Matt. 13:1-9, 18-23), preaching is like spreading seed. Some seeds fall along the path and birds eat them; some seeds fall on rocky ground, where they immediately spring up only to be scorched by the sun; some seeds fall among thorns and are choked off; while other seeds fall on good soil and produce grain. For this reason, the preacher must be realistic about the types of people in the congregation. The church is a covenant community, meaning it belongs to Jesus Christ. Yet within the covenant people there are sincere believers as well as hypocrites. Also, unbelieving people from the world are (or at least should be) in our worship services (Zech. 8:20-23; 1 Cor. 14:20-25).
For this reason, Reformed preaching emphasizes both the law and the gospel. The law does two things. First, it humbles the believer, constantly exposing his sins before the Lord. Second, the law either causes the unbeliever to see his or her sin (if it is accompanied by the work of the Spirit) or hardens the unbeliever who will not acknowledge his or her sin. The gospel does two things as well. First, it comforts and confirms the believer in his or her salvation, constantly reminding of what Jesus did for him or her. Second, the gospel sincerely offers the unbeliever the only means of escaping eternal judgment for his or her sin. As the Canons of Dort say:
Moreover the promise of the gospel is, that whosoever believes in Christ crucified shall not perish, but have eternal life. This promise, together with the command to repent and believe, ought to be declared and published to all nations, and to all persons promiscuously and without distinction, to whom God out of his good pleasure sends the gospel. (2.5)
As many as are called by the gospel are unfeignedly [sincerely] called; for God hath most earnestly and truly declared in his Word what will be acceptable to him, namely, that all who are called should comply with the invitation. He, moreover, seriously promises eternal life and rest to as many as shall come to him, and believe on him. (3/4.8)
Whether the prophets preached to the covenant people of Israel or the nations; whether Jesus Christ preached to Israel, His disciples, or the Gentiles; and whether Paul preached to unbelieving Jews and Gentiles or the various congregations of the New Testament, all these preachers always emphasized the need for genuine repentance and true faith. They did this in such a way that believers were constantly comforted while unbelievers were unceasingly discomforted. With this in mind, we can understand the meaning of the Heidelberg Catechism when it contrasts the idols of the Roman Catholic Church, such as statues, stained-glass windows, and images, with the "lively preaching of [His] Word" (HC, Q&A 98).
This excerpt is taken from Welcome to a Reformed Church by Daniel Hyde_._