This verse states, “But when He had turned about and looked on His disciples, He rebuked Peter, saying, Get you behind Me, Satan: for you savor not the things that be of God, but the things that be of men.” Christ was not implying that Peter was Satan.
Peter was the most outspoken of the disciples. This was not a trait that always served him well. (Notice Mark 14:47 and John 13:6-9.) In the Mark 8:33 account, Satan (the “god of this world” [II Cor. 4:4], and “prince of the power of the air…[working] in the children of disobedience” [Eph. 2:2]) had influenced Peter, causing him to “rebuke Him [Christ].”
Satan knows “…that he has but a short time” (Rev. 12:12). He does not want to give up his hold on this world. Christ came to this earth as a physical, flesh-and-blood human being in order to qualify to replace Satan.
Because of the closeness he felt to Christ, Peter could not humanly accept the fact that Christ would have to die. Satan seized on Peter’s emotional tendencies and influenced him to rebuke Christ as he did. Christ recognized Satan’s influence. Another example of this is found in John 13:27.