Take special care lest you proffer ears to the insidious voices of this secular sect, whose voices furnish death, and avoid in this way all usurpers whether they are called archbishops, bishops or parish priests, so that there is nothing in common between you and them, especially in divine matters...in one word, cling to us: for no-one can be in the Church of Christ unless he is unified with the visible head of the Church itself and is strengthened in the cathedral of Peter.