It is a uniquely Christian institution. Preaching tells what the Bible says about salvation. It sustains and strengthens Christians. Preaching focuses the church on its mission. God has made preaching sufficient for proclaiming His truth.
Revival comes when preaching again becomes central in the activity of the church.
There is no substitute for preaching. Other methods of expression may have their place in God's work, but God's primary method is preaching. John Calvin wrote that one of the marks of a true church is the faithful preaching of God's Word.