and for this reason the unity of the church may not be attacked. Thus the papacy is recognized de facto as an earthly institution, but it is stripped of its aura of a supernatural establishment and foundation. In refuting the opposing position, Luther first had to deal with two central Bible passages, namely, the conferring of the power of the keys in Matt. 16:18–19 and the charge in John 21:15ff. to feed Christ’s sheep. Luther followed that tradition of biblical interpretation which applied the