Jesus warns the disciples of the teaching of the Pharisees and Sadducees.
Jesus contrasts what they think with what the disciples think of Him.
Jesus calls them to deny themselves, when Peter tries to point Jesus away from suffering in Jerusalem.
How is this about Jesus?
The first two points above indicate that the teaching of the Pharisees Jesus warned them against was mainly their response to Jesus. They didn't think He was from God. This is going to bring conflict and suffering, and we need to be willing to have that happen.
Sins this passage points to:
We often want to test God (give me a sign, Lord!) when He has given us plenty already for us to trust Him.
We are caught up in physical stuff like the disciples, who thought Jesus was talking about bread instead of about teaching.
We doubt the church will prevail against the gates of hell.
We don't want to suffer and face rejection for Christ.