The Apostle Paul is reminding the Christians at Rome for the fourth time in verse 20 of their privilege in Christ. He wanted to reiterate the glorious truth concerning their salvation. He contrasted the life of sin before conversion and the life of righteousness therafter again and again. He tells them there is a stark difference. God through Christ has done a marvellous work of grace in their lives freeing them from the oppression and stranglehold of sin in their lives.He uses the word “uncleanness” and the phrase “the infirmity of the flesh” to describe the heinous nature of sin.