He is a true and genuine Catholic who loves the truth of God, the Church, and the Body of Christ; who puts nothing else before divine religion and the Catholic faith, neither the authority nor the love nor the genius nor the eloquence nor the philosophy of any man whatsoever; but, despising all that and being fixed, stable, and persevering in his faith, is determined in himself to hold and believe that only which he knows the Catholic Church has held universally and from ancient times.

St. Vincent of Lerins (400-450AD) on being Catholic, Catholics, and Catholicism