Much of the history of the Reformation depends on the ideas of Martin Luther. Because of him, the revolt was more ecclesiastical than theological, except in the fundamental difference of Protestant dependence on faith for salvation and Catholic dependence on the sacraments of the Church. The basic principle on which Luther based his reconstruction of theology was that individual salvation from sin and its punishment was to be obtained by personal faith in Christ as a sufficient Savior rather than faith in the priest, the sacraments, and the whole system of Catholicism.
Once absolved the emperor hurried home, raised an army and marched on Rome. The pope was aided by the Normans but the contest proved disastrous for Gregory and he died in exile. The quarrel continued until Henry V of Germany compromised with Pope Calixtus II in 1122 and the investiture controversy was settled for a time.