From: Luke 9:18-22
Peter's Confession of Faith
 Now it happened that as He (Jesus) was praying alone the disciples were with Him; and He asked them, "Who do the people say that I am?"  And they answered, "John the Baptist; but others say, Elijah; and others, that one of the old prophets has risen."  And He said to them, "But who do you say that I am?" And Peter answered, "The Christ of God."
First Prophecy of the Passion
 But He charged and commanded them to tell this to no one,  saying, "The Son of Man must suffer many things, and be rejected by the elders and chief priests and scribes, and be killed, and on the third day be raised."
20. "Christ" means "anointed" and is a name indicating honor and office. In the Old Law "priests" were anointed (Exodus 29:7 and 40:13), as were "kings" (1 Samuel 9:16), because God laid down that they should receiving anointing in view of their position; there was also a custom to anoint "prophets" (1 Samuel 16:13) because they were interpreters and intermediaries of God. "When Jesus Christ our Savior came into the world, He assumed the position and obligations of the three offices of priest, king and prophet and was therefore called Christ" ("St. Pius V Catechism", I, 3, 7).
22. Jesus prophesied His passion and death in order to help His disciples believe in him. It also showed that He was freely accepting these sufferings He would undergo. "Christ did not seek to be glorified: He chose to come without glory in order to undergo suffering; and you, who have been born without glory, do you wish to be glorified? The route you must take is the one Christ took. This means recognizing Him and it means imitating Him both in His ignominy and in His good repute; thus you will glory in the Cross, which was His path to glory. That was what Paul did, and therefore he glorified in saying, `Far be it from me to glory except in the cross of our Lord Jesus Christ' (Galatians 6:14)" (St. Ambrose, "Expositio Evangelii Sec. Lucam, in loc.").
Source: "The Navarre Bible: Text and Commentaries". Biblical text taken from the Revised Standard Version and New Vulgate. Commentaries made by members of the Faculty of Theology of the University of Navarre, Spain. Published by Four Courts Press, Kill Lane, Blackrock, Co. Dublin, Ireland. Reprinted with permission from Four Courts Press and Scepter Publishers, the U.S. publisher.