When Paul first taught the truth of justification by faith, it shook the church. It was incredible news at that time. In fact, some theologians responded, "If I'm pardoned, if God is so merciful to forgive me freely by faith alone, then let me sin even more, so God can enjoy giving me more grace!" Those theologians did not understand the gospel.
Because of the cross, God considered everything about our old flesh-man done away with. Paul asked, "Shall we continue in sin that grace may abound?" (Romans 6:1) and he continued quickly, “Certainly not!" I believe Paul was saying, "Why would any Christian, having been set free from such death, go back and resurrect the corpse? Why go back to a life of sin when God wants to take away all guilt and condemnation and give you security and peace? Now, because of the cross, you can serve the Lord with joy and gladness and obey Him in a new obligation called love."
"So," you ask, "are we simply to take by faith the righteousness of Jesus?" Yes, absolutely! That is what the Christian walk is all about—resting by faith in what Jesus accomplished.
Our old man is dead, and the new Man is Jesus. When we put our faith in Him, God fully accepts us. He considers us righteous, hidden in the bosom of His dear Son. So whenever you sin or fail, run quickly to your Lawyer, your Advocate. Confess your failures to Him, and rest in His righteousness.
You may ask, "Don't good works have any place in this doctrine?" Of course they do, but on this condition: Good works cannot save you, justify you or make you righteous or acceptable to God. The only thing that saves you is your faith in what Jesus did!
What did Jesus do? He saved you, pardoned you and accepted you in the beloved—sins, failures and all. God sees you now only in Jesus Christ and that is why we must come to our Savior every time we fall. The blood that forgave and cleansed us the first time we came to Jesus is the same blood continues to keep us until He returns.
Along with this security comes a higher obligation of doing all our works in His strength and power rather than trying to do them on our own. "If by the Spirit you put to death the deeds of the body, you will live" (Romans 8:13).