I found this address by John Piper this morning. It resonates with me and challenges me.
"Let me point to three biblical reasons for believing that preaching is meant to be and to kindle God-exalting worship.
First, I believe it because the Word of God says that everything is to be done in a worshipful, God-centered way: "Whether, then, you eat or drink or whatever you do, do all to the glory of God" (1 Cor 10:31); "Whatever you do in word or deed, do all in the name of the Lord Jesus" (Col 3:17). If everything is to be radically oriented on magnifying the glory of God and exalting the name of Jesus, how much more preaching. Whatever preaching deals with-and it is to deal with everything-it must be done with a view to begetting and sustaining worship-the valuing and cherishing and displaying of the glory of God.
Second, I believe that preaching is meant to exalt the centrality of God because the Word says that God himself exalts his own centrality in all that he does. And preaching is one of the great things that God does. God's Word in Isa 48:11 is like a great banner flying over all his acts from creation to consummation: "For My own sake, for My own sake, I will act; For how can My name be profaned? And My glory I will not give to another." He chose us and predestined us for his glory (Eph 1:6), he created us [believers] for his glory (Isa 43:7), he saved us for his glory (Eph 1:14); he sanctifies us for his glory (2 Thess 1:12). All God does he does to magnify his glory in the earth. Preaching is one of the great things that God does. It is God's work. And therefore the mission of preaching is the mission of God: "I will be exalted among the nations, I will be exalted in the earth" (Ps 46:10). Our aim is worship-the valuing and cherishing and displaying of the greatness and the glory of God.
Finally, I believe that preaching is meant to exalt the centrality of God because the NT teaches that the appointed end of preaching is faith, and faith is the primary covenant requirement of God, precisely because it humbles us and amplifies the trustworthiness and all-sufficiency of God. Repeatedly Paul lines up preaching with faith as its goal: "How shall they believe in Him whom they have not heard? And how shall they hear without a preacher? . . . So faith comes from hearing, and hearing by the word of Christ" (Rom 10:14, 17). "Since in the wisdom of God the world did not know God through its wisdom, God was pleased through the foolishness of preaching to save those who believe" (1 Cor 1:21). "My message and my preaching were not in persuasive words of wisdom, but in demonstration of the Spirit and of power, that your faith should not rest on the wisdom of men, but on the power of God" (1 Cor 2:4-5; cf. also Rom 16:25f; 1 Cor 15:11, 14.) The aim of preaching is to beget and sustain faith. Why? Because faith magnifies the power and trustworthiness of God. This is why Paul loves the model of Abraham: Abraham "grew strong in his faith, giving glory to God, fully convinced that God was able to what he had promised" (Rom 4:20). The heart of saving faith is a spiritual apprehension of the glorious trustworthiness of God in Christ and an earnest embracing of all that God is for us in Christ to satisfy the hunger of the soul.
That is the way Jesus described faith in John 6:35: "I am the bread of life; he who comes to me shall not hunger, and he who believes in me shall never thirst." Believing in Jesus means coming to him for the quenching of our souls' thirst. Faith in Christ is being satisfied with all that God is for us in Jesus. When we experience that, we magnify the preciousness and worth of God, because God is most glorified in us when we are most satisfied in him-which means we worship.
The aim of preaching, whatever the topic, whatever the text, is this kind of faith-to quicken in the soul a satisfaction with all that God is for us in Jesus, because this satisfaction magnifies God's all-sufficient glory; and that is worship. Therefore the mission of all preaching is soul-satisfying, God-exalting worship."