Friends, last week we heard the great Gospel describing Peter’s confession. Because he says correctly who Jesus is, he is declared rock, the firm ground upon which the Church shall be built. And just moments later—our Gospel for today—he is told that he is a Satan, a stumbling block, thinking not as God thinks but as men think. What accounts for this rather remarkable reversal?
In the Gospel, it’s always relatively simple: he doesn’t get the cross. The entire momentum of the life of Jesus is toward the cross. All sorts of forces are trying to keep him from it—some out of self-interest, some out of genuine concern. But they all have this in common: they don’t get it; they don’t get him.
So Peter, probably out of genuine love for Jesus, urges him away from the Passion: “God forbid, Lord! No such thing shall ever happen to you.” Having correctly confessed who Jesus is, Peter promptly forgets what that entails. Being the Son of God, he thought, meant power and lordship, not ignominy and death.