Influence of the church
Christianity endowed this universal constitution with a clearly monarchical cast. The Christian God, it came to be argued, was the sole ruler of the universe, and his laws were to be obeyed. Christians were under an obligation to try to constitute their earthly cities on the model of the City of God.
Both the church and the secular authorities with whom the church came into conflict in the course of the Middle Ages needed clearly defined arrangements of offices, functions, and jurisdictions. Medieval constitutions, whether of church or state, were considered legitimate because they were believed to be ordained of God or tradition or both. Confirmation by officers of the Christian Church was regarded as a prerequisite of the legitimacy of secular rulers. Coronation ceremonies were incomplete without a bishop’s participation. The Holy Roman emperor travelled to Rome in order to receive his crown from the pope. Oaths, including the coronation oaths of rulers, could be sworn only in the presence of the clergy because oaths constituted promises to God and invoked divine punishment for violations. Even in an imposition of a new constitutional order, novelty could always be legitimized by reference to an alleged return to a more or less fictitious “ancient constitution.” It was only in Italy during the Renaissance and in England after the Reformation that the “great modern fallacy” (as the Swiss historian Jacob Burckhardt called it) was established, according to which citizens could rationally and deliberately adopt a new constitution to meet their needs.