Sin brings death but Christ brings new spiritual life.
And if Christ be in you, the body is dead because of sin; but the Spirit is life because of righteousness. (Romans 8:10 KJV)
Knowing Christ personally and living in a spiritual relationship with Him brings about death to sin and a quickening spiritually alive to new life in Him. It is bringing spiritual death to sin and living unto the holiness and righteousness of Christ. Nothing good resides in our physical flesh nor can it because or flesh is innately bent towards the darkness and evil of the god of this world and light and goodness comes from God.
When God’s spirit comes to reside within us we are quickened spiritually alive from the very moment of our new spiritual life being made dead to the sinful desires of the flesh. Dead flesh means dead to things of the flesh and quickened alive means being alive and living unto the new nature of God.
Living unto the things of God is only possible because of the finished work of Christ on the cross at Calvary and is never reliant upon works man can do for himself. Man is in a continual spiritual process, from the advent of his new spiritual life or positional standing in Christ, putting off the works of the flesh which aligned with the dark and evil nature of the god of this world, putting on the righteousness of God as he walks in fellowship with him.