Paul was teacing the people that regardless of the spirit beings that encamped themselves in the invisible realm, that the power of God was much greater, because God had raised Jesus, His Son from the dead with awesome power and seated him at the right hand of God in the heavenly places far above principalities and power and if these people believed in God, they had nothing to worry about because all things were under His feet meaning that Jesus had all powers in His hands and we as Christians should possess the same power and authority to put Satan and his imps under our feet because we are now fighting spiritual warfare.
We have to remember in the 28th chapter of St. Matthew when the two Mary's went to the grave to see their Lord and Savior, an angel met them with the message that "He is not here; for he is risen." When the disciples went up into the mountain as instructed, Jesus came and spake unto them, saying, :