The book of the prophet Zechariah provides a sort of interpretive key for the life and ministry of Jesus. It tells us what the Messiah would do and what kind of figure he would be. The passage that we read from Zechariah for Mass this week emphasizes that the Messiah, curiously enough, would be “pierced.” In our Gospel, Peter correctly identifies Jesus as the Messiah, but then he (and we) are given a lesson in what that means: the Son of Man must be rejected, persecuted and put to death. Jesus the Messiah saves the world precisely by being killed. To understand that is to understand everything about Christian faith.