What then shall we say was gained by Abraham, our forefather according to the flesh? 2 For if Abraham was justified by works, he has something to boast about, but not before God. 3 For what does the Scripture say? “Abraham believed God, and it was counted to him as righteousness.” 4 Now to the one who works, his wages are not counted as a gift but as his due. 5 And to the one who does not work but believes in him who justifies the ungodly, his faith is counted as righteousness, 6 just as David also speaks of the blessing of the one to whom God counts righteousness apart from works:
7 “Blessed are those whose lawless deeds are forgiven,
and whose sins are covered;
8 blessed is the man against whom the Lord will not count his sin.”
When payday rolls around at your place of work how would you react if your boss said to you as he hands you your check, ‘this is my gift to you.’ I know that in my mind I would be thinking ‘gift, this is not a gift, I worked for this check, I earned it, and I deserve to be paid.’
The fact is when you got the job with your employer there essentially was an contract put into place. You work 40 hours a week productively and in exchange they will provide you with a certain wage. Sometimes there is a real contract, but in most cases the contract is implied on their willingness to hire you and your willingness to work for the wage they proposed. So then my work results in wages earned.
When it comes to our salvation Paul wants us to understand that it did not come by our works. If we could work for our salvation that would mean that God would be indebted to us for our works and our salvation would be due to us through our own effort. This would mean that we could boast about what we have accomplished instead of glorifying God for what he has done. Even if God did 99% of the work and we did 1% of the work we would have a claim on God and could boast about even the smallest of our efforts.
However, God rejects our works all together. Nothing we do can gain even the smallest scintilla of our salvation. Our salvation comes to us not by work as wages due, but as a gift from God. It comes to us as 100% from God. He did all the work to bring about regeneration, faith, repentance and finally our justification. It is all a gift, a gift for which God gets all the glory, and it is all of grace.