"So the last will be first, and the first will be last."
Grace doesn't run on a clock
A landowner goes out at dawn to hire workers for his vineyard, then again at nine, noon, three, and five — that last group getting only an hour before quitting time. When evening comes, he pays every one of them the same full day's wage. The workers who started at sunrise are furious. It isn't fair, they say. The landowner's answer is simple: "Are you envious because I am generous?"
It's tempting to read this as a story about labor, but it's really a story about how grace works. It doesn't ration itself by seniority, effort, or how long you've kept the rules. Whether you've shown up at dawn or an hour before closing, the invitation is the same, and so is the welcome. What looks like unfairness from the outside is generosity from the inside.
The question the parable leaves us isn't "was that fair?" It's whether we can rejoice when someone else's grace turns out to be just as large as our own.
"Men cannot be justified before God by their own strength, merits, or works, but are freely justified for Christ's sake, through faith, when they believe that they are received into favor... This faith God imputes for righteousness in His sight."
Augsburg Confession, Article IV — Of Justification · bookofconcord.org