Daily Reading for January 18 • The Confession of St. Peter the Apostle
Peter did not say “you are a Christ” or “a son of God” but “the Christ, the Son of God.” For there are many christs by grace, who have attained the rank of adoption [as sons], but [there is] only one who is by nature the Son of God. Thus, using the definite article, he said, the Christ, the Son of God. And in calling him Son of the living God, Peter indicates that Christ himself is life and that death has no authority over him. And even if the flesh, for a short while, was weak and died, nevertheless it rose again, since the Word, who indwelled it, could not be held under the bonds of death.
From Fragment 190 by Cyril of Alexandria, quoted in Ancient Christian Commentary on Scripture: New Testament Ib, Matthew 14-28, edited by Manlio Simonetti and Thomas C. Oden (Downers Grove, Ill.: InterVarsity Press, 2002).