Vincent of Lérins

Hence [Montanus] richly deserved that it also ought to be said of him and his writings: “If there rises in the midst of you a prophet, you shall not hear the words of that prophet.” And why not? “For,” it is said, “the Lord your God tries you whether you love him or not.” By virtue of these many convincing examples9 from church history and others of the same kind, we must clearly perceive and, according to the rules of Deuteronomy, fully understand that if at any time a teacher of the church deviates from the faith, divine providence permits this to happen in order to test and to try us, “whether we love God or not with all our heart and all our soul.” Since this is so, we may say that a true and genuine Catholic is the person who loves the truth of God, the church and the body of Christ. [Such a person] does not put anything above divine religion and the Catholic faith—neither the authority, nor the affection, nor the genius, nor the eloquence nor the philosophy of any other human being.