Romans 4:6-8 NLT David also spoke of this when he described the happiness of those who are declared righteous without working for it:

Following his flagrant transgression of the law, David later wrote two penitential psalms to praise God for His forgiveness and to express his own joy at being forgiven. Ps.51 and 32 have been a blessing down through the ages to those carrying a heavy burden of guilt. 

In Romans 4 Paul quotes Ps.32:1, 2. Interestingly enough, that passage does not even mention the word “righteousness”. The reason for Paul’s choice lies in the fact that it employs the word “credit’ or “impute”, a central word in Rom.4. 

Yet that all-important word is used in a different sense with David than it was with Abraham. For the latter, Paul tells us that God credited his faith as righteousness. But for David, we find that God did not credit or count his sin to his account. Thus Paul in just a few short verses explains justification as having two aspects – a positive and a negative. First, God counts our faith as righteousness. Second, He does not count our sins against us. Through faith we are clean. 

God did for David what the king could not do for himself. He forgave him, covered his sins, and did not impute his sins to his account. Paul equates David’s experience with righteousness and justification. David’s forgiveness was an act of God’s grace.  

The faith explanation just seems to be too simple. There must be something that we have to do, something that Abraham did. After all, Abraham had been circumcised. That must have counted for something since it is the sign of the covenant. It is all too easy to think that way – to assume that there must be something that we need to do in order to be justified. Faith is good, but faith plus works would be even better. That is the exact attitude that Paul is combating here. He has forcefully argued that justification is God’s gift “apart from works” of any kind v6.  

It was so in Abraham’s case, Paul asserts. He only had to go back to Genesis for that conclusion. Gen.15:6 declared Abraham to be justified even though the circumcision command did not come until Gen.17, 14 years later.