Luke 9:18-20 (ESV)
Now it happened that as he was praying alone, the disciples were with him. And he asked them, "Who do the crowds say that I am?"  And they answered, "John the Baptist. But others say, Elijah, and others, that one of the prophets of old has risen."  Then he said to them, "But who do you say that I am?" And Peter answered, "The Christ of God."
Luke returns to the theme. Who is Jesus? Luke skips quite a chunk of ground that Mark inserts in between these two events. Peter confesses that Jesus is the Christ, right after the feeding of the five thousand. Jesus is the Christ of God, Peter has been convinced by the miracle, the feeding of the five thousand, the one miracle that is recorded in all four gospels the same as the resurrection. There in the feeding of five thousand, loaves blessed by Christ, Peter found life.
Jesus is the Christ. Christ means messiah, the one is a Greek word the other a Hebrew word both meaning anointed. Jesus is the Christ of God, the anointed one of God. One who has been anointed by God. He isn’t a Christ, but the Christ. He is the promised one. He has come to save the world. He has come to fulfill scriptures that remain incomplete without him. He isn’t just a rabbi that one can listen to and take advice from among other rabbis. He is the Christ, and Peter knows this means he will follow him exclusively.