Excerpt from Is Faith Meritorious?

What faith involves and whether it “merits” salvation may be shown by two illustrations. First, picture yourself as a murderer condemned to death and awaiting execution. You are guilty and everyone knows it. You deserve to die. Then you get a letter from the President of the United States which says that he has, by his sovereign power, decided to remit your sentence and let you go free.

The reason he gives for this decision is not that any new evidence has turned up, but rather he simply wants to demonstrate to everyone his power in this declaration of mercy and to transform your disregard for his laws into humble adoration of his merciful sovereignty. He calls your attention to his seal on the letter and instructs you to simply show it to the warden, who will then let you go free—no questions asked.

So you call the guard, show him the letter and get a hearing with the warden. As you enter the warden’s office, you smell the fresh air of life and liberty blowing in his window and you see the tops of trees and a kite flying beyond the wall. You hand him the letter and he reads it. Without a query he orders the guard to get your things. As you leave the gates you turn to look at the massive prison and the row of windows where you had been an hour before. Then you start running and jumping and shouting and laughing and telling everyone, “The President let me out! The President let me out!”

In the second illustration, picture yourself as a poor unskilled laborer who barely can scrape enough together to feed your wife and three children. One day you get in the mail a letter from a famous wealthy philanthropist. The letter says that if you will bring it to his lawyer, the lawyer will pay you a hundred thousand dollars—no strings attached. The reason he gives is simply that he enjoys giving to the poor.

There is no indication why he sent the letter to you and not to another. You need only go pick up the money with the letter. So you follow his instructions and go. Entering the lawyer’s office, you hand him the letter. He says he has been expecting you, writes the check and bids you farewell.

The question that these two stories raise is whether you, in either situation, could properly speak of “meriting” freedom or wealth? You did have to meet a condition: The sine qua non of freedom and wealth was to present the letters from the President and the philanthropist. But to use our definition of merit, was your presenting of the letters an act so valuable to the President or to the philanthropist that they were thus obligated to reward you?

I think the answer is clearly no. Only one thing obligated the President and the philanthropist—their own honor. Insofar as they were committed to maintaining their own honor, it was morally impossible for them to refuse the favor they had promised. In other words, there was something so valuable to them that they were obligated to “reward” it, namely, their own good name.
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Faith is the one human act which morally obligates another person without calling attention to the other person’s honor. Faith in God’s promise obligates him to save the believer not because the quality of faith is meritorious, but because faith is the one human act which calls attention alone to God’s merit, honor and glory and his unswerving commitment to maintain that glory.

From "Is Faith Meritorious?" by John Piper.