You have been dying, you are dying, and at some point in the future you will be dead. This should not be shocking or surprising to anyone, because it is true for everyone, righteous and unrighteous alike. What Jesus told the Jewish opposition was shocking because of what He added about dying in their sins.
The Jews had three major words with three different meanings that were all translated into Greek and English with only the one word, “Sin.” When Jesus used the Greek word for sin, the Jews had to determine His meaning from the context and verb tense.
They knew Jesus was not talking about sin, “the power of evil let loose in the world. He would have said “you will die in the midst of sin” and He would have have been right for every one who has ever lived. We live in a world where systemic evil is all around us, and we all will die in the midst of that evil.
Jesus was not talking about the fallen state of imperfection that everyone is born into. Because of original sin we will always, on this earth, be imperfect in performance. No matter our best intentions, there will be times when we will miss the mark and fall short.
Jesus was talking to them about their personal sin. It was not the sin of others or sin in the world as a whole. It was their sin, and they needed to own it. They were responsible for it and they were estranged from God because of it. It was the sin of knowingly and willfully desiring, thinking, speaking and doing things they knew were wrong and contrary to the will of God and to the cause of righteousness.
Jesus told them they were sinning in rebelliousness against God and would die in a lost sinful condition because of it. Jesus gave them hope. By changing direction they would change their destination. They were shocked that God’s chosen people could be lost. Many were shocked into belief and others into hate. We all live in faith or die in sin.