Call to mind then, the things which I have stated in the two preceding books, and, taking these in connection with them, thou shalt have from me a very copious refutation of all the heretics; and faithfully and strenuously shalt thou resist them in defense of the only true and life-giving faith, which the Church has received from the apostles and imparted to her sons. For the Lord of all gave to His apostles the power of the Gospel, through whom also we have known the truth, that is, the doctrine of the Son of God; to whom also did the Lord declare: “He that hears you, hears Me; and he that despises you, despises Me, and Him that sent Me.”
Irenaeus of Lyons
Against Heresies, Book III
Chapter I