The 2nd mistake the older brother makes is in thinking that his service puts his father in his debt. Looking again at v.29, “these many years I have served you… yet you never gave me a young goat…” he thinks that, as a result of his years of service, his father owes him at least a young goat.
But what does the father do? He doesn’t seem to think he owes his older son anything, while his younger son, who’s devoured his father’s property with prostitutes, is repaid with the best robe the servants can find, and a big party.
In Romans 4:4, Paul says “Now to him who works, the wages are not counted as grace but as debt.”
If you’ve done some work for somebody, your employer owes you a debt. I got some money in my bank account this week, but I don’t look on that money as a gift. I had a pre-arranged agreement with my employer that I would work for a month and they would pay me that amount for it. Since I did the work, the company was in my debt until they paid me for it. However, if someone gave me a cheque for the same amount, without me having done anything for them, I would look on that money differently. If my paycheque is bigger than someone else’s, I might be justified in boasting that I’d done some more valuable work than them, but God won’t let us boast.
Ephesians 2:8-9 says “For by grace you have been saved through faith, and that not of yourselves; it is the gift of God, not of works, lest anyone should boast.”
We’re not allowed to work for our salvation, because then we would be able to boast that we’d earned it, and the preceding verse (Eph 2:7) tells us why we’re not supposed to boast, it tells us that God saved us, not so that we could show off how hard we’re willing to work, but “so that… he might show the immeasurable riches of his grace in kindness towards us in Christ Jesus.” God doesn’t want us to earn wages from him, he wants to show off his own immeasurable riches.
And this applies to sanctification too. In Galatians 3:3, Paul asks “Are you so foolish? Having begun in the Spirit, are you now perfected by the flesh?”
Any progress we make as Christians, we’re being perfected by the Spirit, not by works of law or flesh, so God still gets all the credit for our growing righteousness.
Although I knew this in theory, I still used to have this confused idea that, having been saved by Jesus’ sacrifice on the cross, I was supposed to spend the rest of my life trying to pay him back by doing good things and making myself righteous.
But looking back to 1 Corinthians 4:7, “What do you have that you did not receive?” all the good things I did that I thought were earning me favour with God by paying him back for his grace, all of those came from God in the first place. So rather than paying God back for grace by doing righteous deeds, since God gave us those righteous deeds, the more righteous deeds we do the more we’re in God’s debt! And that’s a glorious thing, because the more God gives us, the more he shows of the immeasurable riches of his grace! (See also Luke 7:36-50; the one who is more in God’s debt loves him more)