For God has done what the law (being weak because of human flesh) was incapable of doing. God sent his own son in the likeness of sinful flesh, and as a sin-offering; and, right there’re in the flesh, he condemned sin.
This was in order that the right and proper verdict of the law could be fulfilled in us as we live not according to the flesh but according to the Spirit.
When Paul says that God sent Jesus to earth in the likeness of sinful flesh, he is saying that He sent Him in the closest relation to sinful humanity possible without becoming Himself sinful.
Through Jesus, God condemned sin, meaning He took away not only sin’s guilt, but its power and dominion over our lives. The law merely shows us what not to do, but does not have in itself the power to hamstring sinful tendencies within us.
When we live according to the power of the Holy Spirit, sin has no power over us, and we automatically fulfill the law’s original intention, not just by keeping the rules, but by having the heart that God originally intended for us to have.