What is the context?
Peter has just confessed Jesus as the Christ and heard His promise to build the church. Matthew now marks a new stage: Jesus begins to explain that He must go to Jerusalem, suffer at the hands of the leaders, be killed, and rise on the third day. Understanding His identity must include understanding this path.
Peter takes Him aside and rebukes Him, insisting that this must not happen. Jesus answers with a severe rebuke of His own. He calls Peter Satan and a stumbling block, then explains the problem: Peter is thinking in human terms rather than according to God's purpose.
Stumbling block is σκάνδαλον, skandalon (SKAN-dah-lon), a snare or something that causes a person to stumble. Thayer's entry includes Peter's action in this verse. The disciple who has spoken truly about Jesus is now trying to turn Him away from the road He says He must take.
The contrast is sharp. A correct confession does not mean Peter already understands everything the Messiah will do. Jesus continues teaching and correcting him. The call to deny oneself and follow in the next verses grows directly out of this encounter.
How is this passage commonly understood?
Christians commonly read this as Jesus preparing His disciples for the necessary suffering and resurrection of the Messiah, with Peter's objection opposing that purpose. Wesley on Matthew 16:21–23 emphasizes the danger of advice that would turn Jesus away from His saving work, while the Catholic Catechism, 554, likewise connects Peter's confession with the difficult revelation of the coming cross.
Where does this fit in God's plan?
After the resurrection, Jesus explains the same necessity from Scripture. In Luke 24:25–27, 44–49, He connects His suffering and resurrection with the Law, Prophets, and Psalms, then with repentance and forgiveness being proclaimed to all nations. What Peter wants to prevent is central to the saving message the disciples will carry.
Hebrews 2:14–18 explains why the Son shares our humanity and passes through death: He defeats the devil's hold through death, frees people enslaved by its fear, and makes atonement for sins. His suffering also belongs to His help for those who are tempted. God's purpose brings rescue through the costly path Jesus accepts.
What is our position?
In What Does Prayer Look Like?, we draw on this announcement when considering Jesus' later prayer in Gethsemane. He already knows the path before Him, yet its cost is real. The study emphasizes honest prayer governed by surrender to the Father's will. Knowing God's purpose does not make obedience painless.