Catechism of the Catholic Church

The truth of Jesus' divinity is confirmed by his Resurrection. He had said: "When you have lifted up the Son of man, then you will know that I am he." The Resurrection of the crucified one shows that he was truly "I Am," the Son of God and God himself. So St. Paul could declare to the Jews: "What God promised to the fathers, this he has fulfilled to us their children by raising Jesus; as also it is written in the second psalm, You are my Son, today I have begotten you.'" Christ's Resurrection is closely linked to the Incarnation of God's Son and is its fulfillment in accordance with God's eternal plan. (445, 461, 422)