"Thus it is written, that the Christ should suffer and on the third day rise from the dead, and that repentance and forgiveness of sins should be preached in his name to all nations, beginning from Jerusalem."
Ever wonder why we read the Old Testament at Mass? A second century man named Marcion did. He was a clever man who was sure he knew better than the apostolic Church what was what. And since, as he thought, Jesus was the "good God" and the God of the Old Testament was a "bad God" whom Jesus had replaced, Marcion decided that we didn't need to bother with the Old Testament anymore now that the New Testament was here! He snipped the Old Testament out, got rid of any references to it in the New Testament books and chopped up his favorite gospel (Luke) in order to "improve" it. The reaction of the Church to all this editing and improving was summed up by Tertullian. He said Marcion had "a pumpkin in place of a brain." The Church insisted that the Old Testament still mattered very much and was still inspired Scripture for the very simple reason that the God of the Old Testament was none other than the God of the New Testament: the Father, Son, and Holy Spirit. The relationship between the Old and New Testaments was not that the New "replaced" the
Old but that the New was hidden in the Old and the Old was only fully revealed in the New. Jesus says exactly the same thing in today's verse. The mystery of Christ is written in the Old Testament by the same Spirit who inspired the New. Today, pay close attention to the way the Old Testament and gospel readings at Mass speak to each other and to us.