He has just explained the suffering, pain, death and resurrection he is going to go through to his disciples. Then one of his closes followers Peter, who had just confessed that Jesus was the Christ, the Son of the living God (Messiah), begins to rebuke (Express sharp disapproval or criticism of (someone) because of their behaviour or actions) him. Then Jesus says “Get behind me Satan!” and refers to peter not having in mind the things of God but of Man. This is important to note as we explore Jesus next command.
“If anyone would come after me, he must deny himself and take up his cross and follow me.”
-Jesus
Simple and straight forward, Jesus here give us the crux of Christianity. He calls us to die to our Selfish Independent Nature and instead walk in the will of God by following him. No longer do we have in mind the things of Man, but the things of God. A. W. Tozer offers relevant and challenging insight in his description of a cross and a throne:
“In every Christian’s heart there is a cross and a throne, and the Christian is on the throne till he puts himself on the cross; if he refuses the cross he remains on the throne. Perhaps this is at the bottom of the backsliding and worldliness among gospel believers today. We want to be saved but we insist that Christ do all the dying. No cross for us, no dethronement, no dying. We remain king within the little kingdom of Mansoul and wear our tinsel crown with all the pride of a Caesar; but we doom ourselves to shadows and weakness and spiritual sterility.”