The marks by which the true Church is known are these: If the pure doctrine of the gospel is preached therein; if she maintains the pure administration of the sacraments as instituted by Christ; if church discipline is exercised in punishing of sin; in short, if all things are managed according to the pure Word of God, all things contrary thereto rejected, and Jesus Christ acknowledged as the only Head of the Church. Hereby the true Church may certainly be known, from which no man has a right to separate himself.