A great question. An illustration will help answer it.
Let’s say we have a vase. It has no flowers, no water in it. It is merely full of air. What is the difference between the air outside the vase and the air inside the vase? The air inside the vase has shape, right? It is the same air in composition, but the air inside the vase has shape. If we take that vase and smash it against the wall, what happens to the air inside of it? Does it die? No, air cannot die. The vase can be in thousands of pieces, but nothing happens to the air, except lose its shape.
When Jesus died on the cross, his body died, but the Spirit of Jesus, the Spirit of God never dies. God took on the form of man, in Jesus. He took on the shape of man, but Jesus was never only man.
On the cross, Jesus paid for our sin and removed the barrier that stood between us and him. Because of his death, we can be at peace with God. Though we were guilty, the justice of God was fully met by Jesus, the Lamb of God who suffered for us. And the love of God was fully expressed in that Jesus willingly laid down his life for us.
You may say, “That’s not fair.” And you’re right. We don’t deserve Jesus’ dying for us. But this was God’s solution for us. Do we tell God how it must be?
Jesus paid our penalty of death, so that we would not need to die for our sins. He wants us to come into relationship with him, to know his love, and to have eternal life.
One more story. A true story, to help you understand what Jesus did for us.
There was a righteous judge who would not take bribes. He was just. Honest. A lady was caught and brought before him. The penalty she might have to pay was a life sentence or a huge sum of money which she did not have.
The judge asked her, “Are you guilty or not?”
And she cried out, “Your honor, I cannot pay the sentence. I cannot pay the money. Please have mercy on me.”
The judge said, “I am asking you, ‘Are you guilty or not? Do you confess?'”
Finally the young lady said, “Your honor, yes, I am guilty.”
He said, “Then you pay the price. Life sentence or the sum of money.” And he closed the case.
She starts screaming and wailing, and they dragged her out of the courtroom to prison. The judge took off the robe, and walked out of the court. He then walked to the treasury. And right there at the treasury, he paid all the money he had and paid the ransom for that girl. Why? Because he loved the girl very much. She was his daughter. And he redeemed his daughter himself, with everything he had.
When the judge took off his robe, he became like any other man. And that’s exactly what Jesus did.
He left heaven, took off the robe of glory, and became like any other man. And he died for us, so our sins would no longer condemn us and keep us eternally separated from God.
All the prophets said that Jesus would come and die for the sins of the world. Jesus is the only hope for mankind to have eternal life.
Back at the beginning with Adam and Eve, God told Satan that an offspring of a woman would crush Satan’s head, and mankind would be redeemed. Jesus’ death and resurrection overcame the power of Satan. Jesus overcame sin, death, and our separation from God…delivering a crushing blow to Satan.