1 Peter 3:18

18 For Christ also died for sins once for all, the just for the unjust, so that He might bring us to God, having been put to death in the flesh, but made alive in the spirit;

Christ suffered and died not because of any sin, for He was a just man His entire life; but He suffered for all of us who are unjust so that He may bring us to God—having our sins paid for. His body was put to death by sinful men, but His inner spirit lived on.

Looking back at verse 17, we can be glad if we suffer for doing what is right; for that is what Christ did. Hence, we are identifying with Him. He suffered and died being entirely righteous. But He went beyond that; He suffered and died for all of us who were guilty of sins. He suffered for our sins.