Duty is one of those words that used to carry great weight but really doesn't anymore. It is still an important concept in military circles, but elsewhere doing something because it's your duty has acquired a negative connotation. "You just say you love me because you think it's your duty." "They just go to church out of a sense of duty."
In the nineteenth century, though, calls to duty were inspirational. Just before the sea battle of Trafalgar, Admiral Nelson sent up signal flags that sent this message to the fleet: "England expects that every man will do his duty." The words electrified not just the sailors, inspiring them to victory over Napoleon, but the English people, who turned the line into a national slogan. William Wordsworth was a Romantic poet with a revolutionary impact, but he wrote an emotional celebration of the concept in his great poem "Ode to Duty."
Duty carries a moral weight, but it is not exactly the same as morality. A soldier might consider it his duty to keep his uniform immaculate and his barracks always ready for inspection, but there is no moral commandment that requires it. A Victorian gentleman might be a womanizer, a gambler, and a wastrel, but if you accused him of failing to do his duty—to his family, his country, or his profession—he might challenge you to a duel.
A duty is an obligation related to a position, office, or station. In Christian terms, duties are the responsibilities that come from a person's vocations.
Luther's Small Catechism teaches the doctrine of vocation with the help of a "Table of Duties." It consists simply of Bible verses that address how pastors and church members, rulers and citizens, husbands and wives, parents and children, employers and employees should carry out their callings. These vocations are all "holy orders"—a term previously reserved for priests, monks, and nuns—for living out the Christian faith.
We have vocations in the family, the workplace, the nation, and the church. That means that we also have duties in each of these estates. Most people still feel some sense of duty in these areas, however vaguely thought through, though the Bible ramps up these duties considerably and charges them with spiritual significance.
A man might consider it his duty to provide for his wife and children. In a traditional family, his wife might consider it her duty to keep the house clean and to keep her family fed. (Even in less-traditional domestic arrangements wherein the wife works as many hours as her husband, she may feel guilty if she shirks these household "duties.")
The Bible has little to say about these kinds of division of labor, but it goes much deeper into God's expectations for these callings. Wives are told to "submit to your own husbands, as to the Lord" (Eph. 5:22). This is the wife's duty. Then husbands are told to "love your wives, as Christ loved the church and gave himself up for her" (v. 25). This is the husband's duty. He is to sacrifice himself for his wife. She is to deny herself for her husband. These duties of mutual self-denial out of love for the spouse may indeed take the form of the husband working hard to put food on the table and the wife working hard to prepare that food and to clean the table, or it may take other forms. But looming behind these mundane family duties is the gospel of Christ. He gave up His life out of love for His church. Those in the church deny themselves in accepting Christ's sacrifice.
The relationship between husband and wife thus exemplifies what Jesus said about the Christian life in general:
If anyone would come after me, let him deny himself and take up his cross daily and follow me. For whoever would save his life will lose it, but whoever loses his life for my sake will save it. (Luke 9:23–24)
The cross refers not just to suffering but to sacrifice, denial, even crucifixion, of the self for someone else's sake. That this cross-bearing is to take place "daily" means that our Lord is not referring to some glorious martyrdom, but to the ordinary, day-by-day tasks of life—vocation.
The purpose of every vocation, according to Luther, is to love and serve one's neighbor. And to love someone involves sacrificing yourself for that person. This happens in every vocation. This is the parents' duty to their children, and their children's duty to their parents. This describes our duties to our country, in our vocation as citizens, and it describes our duties in the church.
On the job, the duties might be as simple as showing up to work on time, following instructions, and putting in an honest day's work. Instead of sleeping in, taking it easy, and otherwise following his personal inclinations, the worker denies himself for the sake of his customers, his boss, and his fellow workers, as well as for his family that he is providing for. When he comes home bone-tired, we might say that he has presented his body as a living sacrifice (Rom. 12:1).
And yet, there is no merit, no special reward, for doing one's duty. Jesus makes that crystal clear in the parable that concludes, "When you have done all that you were commanded, say, 'We are unworthy servants; we have only done what was our duty' " (Luke 17:10).
We are saved by grace through faith in Christ and by the work of His sacrifice, not by our own works or sacrifices. But Christ then calls us to arenas of service in ordinary life, of "faith working through love" (Gal. 5:6). He calls us to faithfulness in our multiple vocations. This may or may not involve big things, but it always involves little things (Luke 16:10), such as simply doing our duty.