The Faithful Exercise of Church Discipline The Reformers’ third mark was the faithful exercise of church discipline. Here they employed such passages as the following: Matthew 18:17: “If [a sinning brother] refuses to listen to [two or three concerned Christians], tell it to the church; and if he refuses to listen even to the church, treat him as you would a pagan or a tax collector.” Acts 20:28–31a: “Keep watch over yourselves and all the flock of which the Holy Spirit has made you overseers. Be