"Preaching involves teaching, but it is much more than that. The sacramental aspect of the Word--that is, its role as a means of grace--underlies Reformation teaching. The preaching of the gospel not only calls people to faith in Christ; it is the means by which the Spirit creates faith in their hearts (as expressed in Q 65 of the Heidelberg Catechism). In evangelical theologies, this sacramental aspect of God's Word is often marginalized by a purely pedagogical (instructional) concept. It is therefore not surprising that when the Word is reduced to its didactic function there arises a longing of the people to encounter God here and now through other means. However, by affirming its sacramental as well as the regulative (canonical) character, we can recognize the Word of God's working and ruling, saving and teaching."
Michael Horton, The Christian Faith: A Systematic Theology for Pilgrims on the Way (Grand Rapids: Zondervan, 2011), 754-5.