Luther was anxious, indeed, apart from this special reason, to be allowed to defend in a public disputation the truth for which he was called a heretic; he had made this proposal in vain to the legate at Augsburg. He now demanded to be admitted to the lists at Leipzig. He wished in particular, to take up the contest, openly and decisively, about the Papal primacy. His friends just on this point grew anxious about him. But he prepared his weapons with great diligence, studying thoroughly the ecclesiastical law-books and the history of ecclesiastical law, with which until now he had never occupied himself so much. Herein he found his own conclusions fully confirmed. Nay, he found that the tyrannical pretensions of the Pope, even if more than a thousand years old, derived their sole and ultimate authority from the Papal decretals of the last four centuries. Arrayed against the theory of that primacy were the history of the previous centuries, the authority of the Council of Nice in 325, and the express declaration of Scripture. This he stated now in a thesis, and announced his opinion in print. We have already noticed the high importance of this historical evidence in regard to matters of belief, as well as to the entire conception of Christian salvation, and of the true community or Church of Christ. The real essence of the Church is shown not to depend on its constitution under a Pope. And the course of history, wherein God allowed the Christians of the West to come under the external authority of the Pope, just as people come to be under the rule of different princes, in no way subjected, or should subject, the whole of Christendom to his dominion. The millions of Eastern Christians, who are not his subjects, and who are therefore condemned by the Pope as schismatics, are all, as Luther now distinctly declares, none the less members of Christendom, of the Church, of the Body of Christ. Participation in salvation does not exist only in the community of the Church of Rome. For Christendom collectively, or the Universal Church, there is no other Head but Christ. Luther now also discovered and declared that the bishops did not receive their posts over individual dioceses and flocks until after the Apostolic period; the episcopate therefore ceases to be an essential and necessary element of the Church system. What, then, is really essential for the continuance of the Church, and how far does it extend? Luther answers this question with the fundamental principle of Evangelical Protestantism. The Church, he says, is not at Rome only, but there, and there only, where the Word of God is preached and believed in; where Christian faith, hope, and charity are alive, where Christ, inwardly received, stands before a united Christendom as her bridegroom. This Universal Church, says Luther, is the one intended by the Creed, when it says 'I believe in a Holy Catholic Church, the communion of saints.'