(The Puritans believed in) the supreme importance of preaching. To the Puritans, the sermon was the liturgical climax of public worship. Nothing, they said, honours God more than the faithful declaration and obedient hearing of His truth. Preaching, under any circumstances, is an act of worship, and must be performed as such. Moreover, preaching is the prime means of grace to the church.
A Quest for Godliness: The Puritan View of the Christian Life, Crossway, 1990, p. 281.