Now when a man works, his wages are not credited to him as a gift, but as an obligation. However, to the man who does not work but trusts God … his faith is credited as righteousness. Romans 4:4-5
It’s rather obvious that when we are employed we receive a wage. As Paul explains we don’t consider the money a gift. After all, we have given up our time and put in some effort in order to do the work so we expect a wage. It’s the employer’s obligation to us. By using this illustration Paul makes it clear that we don’t work for our salvation. Salvation is a gift—not something we are owed because of the time we give up or the effort we put in. It’s a gift we receive when we trust God.
Later in the chapter (verses 13-16), Paul talks about the difference between a contract (or law) and a promise. In a contract, the two people involved each contribute something. When you buy a house one person agrees to hand over a certain sum of money and the other person agrees to hand over the house. Both parties contribute something of equal value. But in a promise, one person agrees to something without the other person contributing anything. It’s God who makes the promise agreeing to grant us salvation without us making a contribution. “Therefore, the promise comes by faith, so that it may be by grace and may be guaranteed to all Abraham’s offspring” (verse 16).
In both these illustrations, Paul wants us to see that we receive salvation by faith. We cannot earn it or buy it. Yet perhaps what God asks is harder. He wants us to trust, believe, and accept.