Since the fall of man in the Garden of Eden, God set in motion a plan for our salvation. God made the first sacrifice and covered Adam and Eve, then sent them into the world. He also made a promise.
Genesis 3:15 (ESV)
15 I will put enmity between you and the woman, and between your offspring and her offspring; he shall bruise your head, and you shall bruise his heel.”
Here the promise is made that a redeemer will come to deliver man from the power of Satan. God provided a way for the fallen man to be saved. Christ is afflicted in our afflictions. Therefore His heel is bruised, but by Christ death on the cross, the final blow is delivered to the head of Satan and he is defeated.
Jesus Christ has defeated the kingdom of Satan, and we have nothing to fear, not even death. It is by dying that we are set free to be with the Father in heaven.