When the devil starts to speak to us, he creates a wedge between ourselves and our LORD. Jesus rebuke puts the devil in his place. Jesus wasnt speaking to Peter. He was speaking to the devil telling him to get behind Him. Nothing can come between our LORD and ourselves, especially the devil. Matt 16:2323 But He turned and said to Peter, “Get behind Me, Satan! You are an offense to Me, for you are not mindful of the things of God, but the things of men.”