Hildebrand, who took the name Gregory VII when he ascended to the Papacy, is considered one of the most significant popes of the Middle Ages. He attempted sweeping reforms in the Church and took a stand for the primacy of the papacy over secular authorities, a policy that was epitomized in his conflict with Emperor Henry IV. His life's work was based on his conviction that the church was founded by God and entrusted with the task of embracing all humankind in a single society in which divine will is the only law; that, in her capacity as a divine institution, she is supreme over all human structures, especially the secular state; and that the pope, in his role as head of the church, is the vice-regent of God on earth, so that disobedience to him implies disobedience to God: or, in other words, a defection from Christianity. A controversial Pope who was once regarded as an ambitious tyrant, most modern historians have revised this perspective, viewing him as sincerely pursuing justice. In his own lifetime the Church suffered division, and he himself incurred much criticism; but Gregory's example and the activities of his successors did much to regenerate the Church.