First: Our worship is a participation, mediated by the Spirit, in Christ’s Communion with the Father.
In this Trinitarian picture of worship, where does preaching fit in? Well, there is an eternal “conversation” happening among all the members of the Trinity. The divine words of Creation are presented as an “overflow” of this divine conversation. So to me, preaching is a Spirit-“infused” (and humanly articulated) mediation of the words between the Father, the Son, and the Holy Spirit.
Because the Spirit enables our union with Jesus, and because Jesus is joined to the Father, we find ourselves mystically and intimately in union with the whole Trinitarian God Himself. And so, preaching is–in a sense and at its best–an articulation and “listening in” on this eternal “trialogue” within the Godhead.
The world having been created through and for the Son means that the Father’s words to the Son are now his words to and for us. And this Word that is spoken to the Son by the Father is the Gospel. When it is offered to humans, this eternal, mysterious articulation of the Gospel in the Godhead is always mediated and contextualized in order to be received and perceived by the hearer. This is why the Bible is the way it is.
Theologically, the Bible is God’s testimony of His work in the world in Jesus Christ. It is made understandable and God is made known to us through these Scriptures by way of the Spirit. I don’t really think there’s anything mystical, divine, or special about those precise words themselves. The Bible is not passive, special “revelation”, nor is it “The Word”–Jesus is. The Bible is the place where the “revealing” of God occurs by the Spirit when it’s united to Faith.
Following the Bible’s lead, then, I’d say that Preaching is the bearing witness of the Father’s testimony about the Son, enabled by the Holy Spirit.
The Trinity helps us keep preaching personal rather than merely laying down a bunch of rules. We offer a Person in our preaching. A renewed emphasis on the Spirit helps keep preaching embodied rather than abstract. Our preaching is not about God, it is imbued with God; it is not an exposition on God to his people, but an extending of God to his people.
We believe Christ is our forerunner in all aspects of worship–even Preaching. Jesus has come to earth as God’s sermon to us. If Theology is “thinking God’s thoughts after him”, then preaching would be “Preaching God’s words after him.” And his Word is always a personal, covenantal one that is embodied in the person and work of Jesus Christ, and applied and made real to us by the Spirit.
As the Catholic Catechism says, we are not a people of the book, we are a people of the Word. I love that. Keeping the Trinity in mind moves preaching away from the realm of simple “exegesis” and “exposition” and into an extending of the person of Christ to the world by the Spirit.
For now, that’s all I’ve got.