John Cassian, On the Incarnation of the Lord, Against Nestorius IV.12: How the title of Saviour is given to Christ in one sense, and to men in another

“Thou,” he says, “art our God, and we knew Thee not, O God of Israel the Saviour.” Although holy Scripture has already shown by many and clear tokens, who is here spoken of, yet it has most plainly pointed to the name of Christ by using the name of Saviour: for surely the Saviour is the same as Christ, as the angel says: “For to you is born this day a Saviour who is Christ the Lord.” For everybody knows that in Hebrew “Jesus” means “Saviour,” as the angel announced to the holy Virgin Mary, saying: “And thou shalt call His name Jesus, for He it is that shall save His people from their sins.” And that you may not say that He is termed Saviour in the same sense as the title is given to others (“And the Lord raised up to them a Saviour, Othniel the Son of Kenaz,” and again, “the Lord raised up to them a Saviour, Ehud the son of Gera”), he added: “for He it is that shall save His people from their sins.” But it does not lie in the power of a man to redeem his people from the captivity of sin,—a thing which is only possible for Him of whom it is said, “Behold the Lamb of God, which taketh away the sin of the world.” For the others saved a people not their own but God’s, and not from their sins, but from their enemies.