The punishment of the believer's sin, God laid on Christ. He bore that in our place. Without Christ dying for your sin, you could not have had eternal life in heaven with God. Christ dies so that those who believe in Him have eternal life.
1 Peter 2
21
For to this you were called, because Christ also suffered for [e]us, leaving [f]us an example, that you should follow His steps:
22 “Who committed no sin,
Nor was deceit found in His mouth”;
23 who, when He was reviled, did not revile in return; when He suffered, He did not threaten, but committed
Himself to Him who judges righteously; 24
who Himself bore our sins in His own body on the tree, that we, having died to sins, might live for righteousness—by whose [
g]stripes you were healed. 25
For you were like sheep going astray, but have now returned to the Shepherd and [h]Overseer of your souls.
The punishment of the unbeliever's sins, as in the wrath of God, still abides on them. They still live in their sins, and will perish in them.
But we who believe died to sin. Sin no longer reigns over us.
John 3:36
He who believes in the Son has everlasting life; and he who does not believe the Son shall not see life, but the
wrath of God abides on him.”
John 8
21 Then Jesus said to them again,
“I am going away, and you will seek Me, and will die in your sin. Where I go you cannot come.”
22 So the Jews said, “Will He kill Himself, because He says, ‘Where I go you cannot come’?”
23 And He said to them, “You are from beneath; I am from above. You are of this world; I am not of this world. 24
Therefore I said to you that you will die in your sins; for if you do not believe that I am He, you will die in your sins.”
25 Then they said to Him, “Who are You?”
And Jesus said to them, “Just what I have been saying to you from the beginning. 26 I have many things to say and to judge concerning you, but He who sent Me is true; and I speak to the world those things which I heard from Him.”
27 They did not understand that He spoke to them of the Father.