“You, dearly beloved, whom I address in no less earnest terms than those of the blessed apostle Peter, “a chosen race, a royal priesthood, a holy nation, a people for God’s own possession,” built upon the impregnable rock, Christ, and joined to the Lord our Savior by His true assumption of our flesh, remain firm in the faith, which you have professed before many witnesses and in which you were reborn through water and the Holy Spirit, and received the anointing of salvation and the seal of eternal life. But “if anyone preaches to you anything besides that which you have learned, let him be anathema”; refuse to put wicked fables before the clearest truth, and what you may happen to read or hear contrary to the rule of the catholic and apostolic creed, judge it altogether deadly and diabolical… Indeed, they put on a cloak of piety and chastity, but under this deceit they conceal the filthiness of their acts, and from the recesses of their ungodly heart hurl shafts to wound the simple… A mighty bulwark is a sound faith, a true faith, to which nothing has to be added or taken away, because unless it is one, it is no faith, as the apostle says, “one Lord, one faith, one Baptism, one God and Father of all, who is above all and through all and in us all.” Cling to this unity, dearly beloved, with minds unshaken, and in it “follow after” all “holiness.” In it carry out the Lord’s commands, because “without faith it is impossible to please God,” and without it nothing is holy, nothing pure, nothing alive, “for the just lives by faith,” and he who by the devil’s deception loses it is dead though living, because as righteousness is gained by faith, so, too, by a true faith is eternal life gained, as our Lord and Savior says. And this is life eternal, that they may know You, the only true God, and Jesus Christ, whom You have sent. May He make you to advance and persevere to the end, who lives and reigns with the Father and the Holy Spirit, forever and ever. Amen.                —Leo the Great”