David Platt is the author of the excellent Radical and a preacher with extraordinary fire and passion for disciple-making. He says in this excellent talk called Disciple-making that Robert Coleman's "The master plan of evangelism" is the most important book he has read outside of the Bible.
He offers this quote from it:
"Disciple-making men and women is the priority around which our lives should be oriented. The great commission is not a special calling or a gift of the Spirit, it is a command- an obligation incumbent upon the whole community of faith. There are no exceptions: bank presidents and automobile mechanics, physicians and school teachers, theologians and home-makers, everyone who believes on Christ has a part in his work. The great commission is a life-style that encompasses every child of God. Here the ministry of Christ comes alive in the day by day activity of discipling whether we have a secular job or an ecclesiastical position. A Christ-like commitment to bring the nations into the eternal kingdom should be part of it. If the making disciples of all nations is not the heartbeat of our life something is wrong- either our understanding of Christ's church or our willingness to walk in his way"