In Romans 4, Paul contrasts the ideas of “works = righteousness” with “faith = righteousness.” Abraham was counted as righteous in the sight of God because of his faith, not because of his works. The important detail here is that he was counted or credited with righteousness. He was not made righteous himself. This can be described today as the difference between Jesus’ death and resurrection and the gift of the Holy Spirit. Through Christ, we are counted, or credited, with righteousness. It is not us, but Christ alone. Once we receive that credit, the Holy Spirit begins to make us righteous through divine intervention as we respond to conviction and open our lives to Him.
Many in Paul’s time believed that adhering to the law would prove someone to be a man of God. Others believed you needed to be circumcised to be counted as righteous. Paul debunks both these theories by focusing on faith alone, and uses the Old Testament patriarch, Abraham, before his good deeds or his circumcision. It was a heart choice to trust and follow God under any and all circumstances.
The solution in the Old Testament and the solution today remain the same. Sin cannot be defeated by the works of man. It can only be defeated by God himself. When we put our faith in His plan for Salvation, we become a completely new person.