Gospel: Matthew 16: 21-27
In the passage prior to today's Gospel portion, Peter provided an insightful answer about Jesus, and for that Jesus praised him. Since then, apologists have used that passage to create an entire ecclesiology, ignoring two important elements. The first is today's portion, an event that takes place just after Peter's confession. Here, Peter gets it very wrong about Jesus and his mission, for which Jesus calls him a Satan, rebuking him in the most severe terms.
Peter had made true statements about Jesus, that he was Messiah and Son of God, but Peter did not understand at all what those statements meant. For him, the idea of Jesus being arrested and put to death at the hands of the state and religious leaders made no sense. The Messiah was supposed to drive out the occupying empire and purify the religion of Israel, returning her to some period of past glory, making Israel great again. But Jesus is not that figure at all - not then, not now.
The second error of the apologists is in thinking that the Gospels exist to justify our own notions of ecclesiology and theology. The Gospels exist for us to know the Lord Jesus and to become like him in our lives. They document our own moments of insight as well as our own misunderstandings about Jesus. Our own lives are reflected in the figures of the disciples in our own walk with Jesus. If we want a lot of wrong answers, follow the apologists. If we want to know Jesus better, place yourself in the Gospel itself.