2 Corinthians 5:21
For He made Him who knew no sin to be sin for us, that we might become the righteousness of God in Him.

Our Lord Yshua took our place and became the sin for us. That is the individual sin of rebellion and disobedient nature in us. It is not about the wrong things that we do in many instances in our lives. Only God who is perfect Himself can be the perfect sacrifice. We cannot redeem ourselves - someone had to do it for us. The power of Yshua's work on the cross must be accepted by us and lived by us, not just knowing about it.