Satanic Situation (Matthew 16:21-28)

The prophets and the apostles are the bedrock for the Lord’s church.  Peter, the spokesmen for the apostles, is the one who affirms with absolute certainty that Christ is the messiah.  He is the redeemer, the Christ, the Son of God sent to do the Father’s mission.  It would seem that such a strong affirmation is only going to bring Peter to submission.  However, the Christ rebukes Peter in a strong way.  Why is Christ’s mission so difficult to embrace?