Now to him who works, the wages are not counted as grace but as debt. (Romans 4:4)
In continuing his example of Abraham, Paul refers to “him who works.”
Who is this person “who works?” What is Paul talking about?
“Him who works.”
Who then is the “worker?” He can be no other than the man who has earned acquittal as “wages.” He is the man who has successfully completed his task before God and in whose debt God is. He’s the man who has moved grace right out of the picture by successfully performing the task laid on him by God. And who is that but the sinless man? The “worker” is not just an obedient man but the sinlessly obedient man. To what other man does God owe acquittal? - McGuiggan, Romans, 141
The one “who works” has earned payment from God - he has put God in his debt. God owes him something.
What person would God “owe” an innocent verdict at Judgment? Well, the person who had done nothing wrong - the person who had never sinned!
If you never sin, you don’t need God’s grace to be pronounced innocent - because you have earned the verdict of “innocent.”
Of course, you probably recognize where Paul is going with this point, the same as me.
Not even Abraham was a sinless man - so he had not put God in his debt. God did not owe him “righteousness” (Romans 4:1-3).
Paul continues to drive home this point - if you have sinned, you cannot stand on your own record and be pronounced “innocent” by the Judge.
If you have sinned, you cannot “earn” your way back into the righteous column.
Paul continues to move us toward Jesus Christ as the only way of salvation and justification (Romans 1:16-17).