This Sunday's Gospel continues the dialogue between Jesus and Simon, the Rock on which Jesus will build his Church. What happens is, quite literally, scandalous. Jesus follows his granting of primacy to the freshly named Peter with the first prediction of his passion (and resurrection). In response Peter rebukes Jesus and says, “God forbid. Lord! No such thing shall ever happen to you.” Whereupon Jesus turns to Peter with strong words: “Get behind me, Satan! You are an obstacle to me. You are thinking not as God does, but as human beings do.” The word behind “obstacle” is skandalon, literally “stumbling block.” The foundation stone has become a stumbling stone. “Satan” (adversary) is already such a shocking term that we scarcely notice skandalon.
We know, from the Acts of the Apostles and from tradition, that Simon was indeed enabled by the grace of God to become the rock the Church needed. Like Jeremiah in today's First Reading, and like another initially recalcitrant instrument (Paul), Peter was soon impelled to generous service by a fire in the belly.Paul himself, in the Second Reading (from Romans), supplies a stunning image for Christian service that deserves our attention. “Offer your bodies,” he writes, “as a living sacrifice, holy and pleasing to God, your spiritual worship.” As Jesus drew from Temple tradition to speak of building on a rock, Paul too draws from the realm of the Temple. Israel's practice had been to offer up the bodies of dead animals in Temple worship. Now Paul—in the spirit of Isaiah, Micah, and Psalm 51—says that the best offering to God is not a dead animal body but your own living one, not in suicidal immolation but in the very living out of your life. The rest of Romans (Rm 12:3ff) spells that out as building up the body of the Church by using one's gifts in mutual service, hospitality, prayer, and love of enemies.