The first mark of a healthy church is expositional preaching. It is not only the first mark; it is far and away the most important of them all, because if you get this one right, all of the others should follow… If you get the priority of the Word established, then you have in place the single most important aspect of the church’s life, and growing health is virtually assured, because God has decided to act by His Spirit through His Word… The congregation’s commitment to the centrality of the Word coming from the front, from the preacher, the one specially gifted by God and called to that ministry, is the most important thing you can look for in a church.
Mark Dever