The Great Western Schism that followed upon the residence at Avignon divided Christian Europe into hostile camps, and snapped the bond of unity which was already strained to the utmost by political and national rivalries. Sincere believers were scandalised at the spectacle of two or three rival Popes, each claiming to be the successor of St. Peter, and hurling at his opponents and their supporters the severest censures of the Church. While the various claimants to the Papacy were contending for supreme power in the Church, they were obliged to make concession after concession to the rulers who supported them and to permit them to interfere in religious affairs, so that even when peace was restored and when Martin V. was universally recognised as the lawful Pope, he found himself deprived of many of the rights and prerogatives, for which his predecessors from Gregory VII. to Boniface VIII. had struggled so bravely.
Nor was this all. In their efforts to bring about a reunion, and despairing of arriving at this happy result by an agreement among the contending Popes, many honest theologians put forward principles, which, however suitable to the circumstances of the schism, were utterly subversive of the monarchical constitution of the Church. They maintained that in case of doubtful Popes the cardinals had the right to summon a General Council to decide the issue, and that all Christians were bound to submit to its decrees. In accordance with these principles the Council of Constance was convoked, and, elated with the success of this experiment, many of the more ardent spirits seemed determined to replace, or at least, to limit the authority of the Popes by the authority of General Councils summoned at regular intervals. The Pope was to be no longer supreme spiritual ruler. His position in the Church was to be rather the position of a constitutional sovereign in a state, the General Council being for the Pope what modern Parliaments are for the king.
Fortunately for the Popes such a theory was completely discredited by the excesses of its supporters at the Council of Basle, but it served to weaken the authority of the Holy See, and to put into the hands of its opponents a weapon which they were not slow to wield whenever their personal interests were affected. Henceforth appeals from the Pope to a General Council, although prohibited, were by no means unfrequent.
Yet in spite of all these reverses, had the Church been blessed with a succession of worthy Popes burning with zeal for religion, free to devote themselves to a thorough reform, and capable of understanding the altered political and social conditions of the world, the Papacy might have been restored to its old position. But unfortunately the Popes from Nicholas V. to Leo X. were not the men to repair the damage that was done, or to ward off impending danger. The calamities that threatened Europe from the advance of the Turks, and the necessity of rousing its rulers to a sense of their responsibilities occupied a large share of their attention; while the anxiety which they displayed in the miserable squabbles of the Italian kingdoms, sometimes out of disinterested regard for the temporal States of the Church, as in the case of Julius II., more frequently from a desire of providing territories for their unworthy relations, left them little time to safeguard the general well-being of the Church. In case of some of them, too, if one may judge them by their actions, the progress of Humanism seemed to be nearer to their hearts than the progress of religion.