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On Righteousness, Oaths, and Usury
This text is a translation of Wolfgang Musculus’ commentary on Psalm 15 and his related appendices on the topics of oaths and usury. In these selections from his expansive exegetical work, Musculus presents a theological exposition of the psalm and gives guidance in matters of enduring relevance for Christian living—particularly how to preserve truth and honesty in one’s relationships, speech, and economic practices.
- GenresTheology
160 pages, Paperback
First published December 1, 2013
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Displaying 1 - 3 of 3 reviews
March 24, 2026
Among the many ways to tell if your spaghetti is cooked, there was once a brief fad of throwing it at the wall. If it stuck, dinner was ready. As you can imagine, the fad did not last in my house. Spaghetti is hot, for one. And to throw it, you must hold that steaming noodle in your hand. But more importantly, there are far too many places in my kitchen for undercooked pasta to land. I am not interested in feeding the crack between the countertops and the stove. I could not help but think of that method while reading "On Righteousness, Oaths, and Usury" by Wolfgang Musculus (Not to be confused with the little green monster from the old Mucinex commercials). At times the book feels like someone grabbed a handful of theological spaghetti and started throwing it, hoping something was bound to stick.
The primary text is a short commentary on Psalm 15. It focuses on righteousness, doing what is right even when it is difficult. That is a very Christian concern, and Musculus treats it with the seriousness you would expect from a Reformed theologian. But most of the book hides in two appendices, and both feel like they wandered in from another room.
The first appendix, "On Oaths," responds to Anabaptists who refuse to swear oaths on theological grounds. Musculus argues that oaths are not only permissible but good. They do not violate the Third Commandment. Instead, they help Christians keep their word when righteousness is hard. It is an interesting argument. It is also not the reason most people will pick up this book. The second appendix, "On Usury," is.
This is where things finally get interesting, and it is the only reason this book earns three stars instead of one. Musculus defines usury as unjust profit gained at the expense of others. Not just bad loans. Not just shady interest rates. Any gain that comes from squeezing your neighbor. I could not help but think of Calvin while reading this section. Calvin argues that injustice begins when one person thinks he is more than another. That idea sits right at the center of Musculus’ argument. Usury is not just bad economics. It is unjust gain over another.
Musculus also points out something that almost feels offensive to my little Presbyterian ears. Pre-Trent Catholicism took usury seriously! Canon law had special protections against it. Banks could not simply do whatever they wanted but were limited in how they could profit from others. Of course, through some creative accounting and a loose interpretation of the law, people eventually found ways around those rules. Musculus’ point is simple. Legal does not mean permissible. Some things remain objectively sinful even when the law says its permissible.
So why read this now? Because we as a society have largely forgotten that usury is a sin.
It is easy to recognize slavery as sin. We recognize theft as sin. Most of us even recognize wage exploitation as sin. But usury slipped through the cracks of supposed progress. Usury today looks like predatory lending, absurd rent, manufactured inflation, hidden fees, sports gambling, subscription based economics, literally all of StubHub, and lotteries that prey on the poor. We call all of these normal parts of living in a free market society. Spend five seconds on LinkedIn and you will probably see them praised as clever innovations.
But the real weight of Musculus’ argument is not economic. It is pastoral. Usury is not just out there in banks and corporations. It lives much closer to home. It shows up in the quiet decisions we make when we benefit at someone else’s expense. It shows up when we accept a price we know is unfair. When we take advantage of a situation because it works in our favor. When we profit without asking who paid for it.
If Musculus is right, then usury is not just a societal sin. It is a personal one. That is a harder pill to swallow. It is easy to condemn obvious exploitation. But usury hides. We are often far too quick to justify it as an unfortunate but unavoidable feature of the free market.
Let me take a moment to say that I am generally a fan of free markets. I might even suggest Adam Smith’s invisible hand sounds a lot like the way I imagine a sovereign God might involve himself in the economic affairs of his people. But somewhere along the way, from Max Weber’s "The Protestant Ethic and the Spirit of Capitalism" to our present age, we began to baptize usury as a Christian virtue. We tell ourselves it's okay to exploit others as long as its in the name of “share holder value” and the “bottom line.” It's okay to shop from TEMU even though they literally enslave people, because I am getting a heck of a deal. It's okay to charge the artificially inflated “market price” for my rental property, even though I am profiting 10 fold and keeping a usable home off of the market because I am laying up a nest egg for myself. And we accept it as normal.
Part of that acceptance runs on a powerful myth. One day I might be rich. But even the rich have duties toward their neighbors. Wealth does not erase responsibility. A society without guardrails eventually devours itself.
Musculus pushes us even further. He reminds us that righteousness is not merely avoiding evil. It is loving your neighbor in how you live, trade, and earn. The real question is not “Did I break a rule?” It is “Did I deal justly? Did I love mercy? Did I walk humbly before God?” That changes everything!
TGC recently ran an article that said, “your bank account is not neutral.” That means, your purchases are not neutral. Your wages, your investments, your side hustles. None of it is neutral. We are either being righteous with what God has entrusted to us, or we are not. Morality does not have a middle ground.
Usury, then, is not merely a failure of economics. It is a failure of worship. When we unjustly profit at the expense of others, we do not merely break the Eighth Commandment, “You shall not steal,” or the Tenth, “You shall not covet.” In a deeper sense, we take the Lord’s name in vain. We claim to belong to a just and generous God, yet act as if provision depends on how much we can squeeze out of other people.
I watched a YouTube video recently about a business using a pawn shop style model that effectively robbed an elderly man of $200,000 while staying within the bounds of the law. The video kept using the phrase “restorative justice,” and I found myself a little uncomfortable with the word. It sounded like another academic buzzword from critical theory.
But in truth, restoration is exactly what God does. God does not merely punish sin. He takes it upon himself. He does not leave us to fend for ourselves. He gives us Christ’s righteousness. Where secular theories hope the market or the state will eventually produce justice, Scripture begins somewhere deeper. A just society requires just people. Just people come from a just God who saves sinners.
So I find myself asking uncomfortable questions. Where have I benefited from injustice? Where have I called something normal that Scripture might call sin? Where have I confused profit with blessing? For what it is worth, I still find myself agreeing, at least in part, with Adam Smith. Free markets can work. I mean, I voted for Gary Johnson in 2016 for crying out loud. But markets do not work on their own. They need guardrails. A Christian society cannot shrug at the suffering of its people and call it efficiency.There was a moment when deregulation became the buzzword of the political moment. If we deregulated banks, airlines, and business in general, the economy would supposedly correct itself. But history shows that when business is left entirely unchecked, it tends to draw more and more blood.
Left to our own devices, without the restraining hand of God, there is not a single person alive who will eventually say, “I have had enough.” The temptation to accumulate more is endless. That does not mean wealth itself is sinful. Scripture never says that. Providing for your family is good. Building something and passing it on is good. Money itself is not evil. But profiting unjustly from others is.
Somewhere along the way we replaced the American Dream with the nightmares of hustle culture. And people buy into it because they are trying to survive in a system that squeezes them from every direction. There was a time when a door to door salesman could reasonably expect to own a home and provide for a family. That world feels very far away now. In many ways we built an entire way of life on pretending usury is not a sin. We call it normal. I am not convinced it is.
The primary text is a short commentary on Psalm 15. It focuses on righteousness, doing what is right even when it is difficult. That is a very Christian concern, and Musculus treats it with the seriousness you would expect from a Reformed theologian. But most of the book hides in two appendices, and both feel like they wandered in from another room.
The first appendix, "On Oaths," responds to Anabaptists who refuse to swear oaths on theological grounds. Musculus argues that oaths are not only permissible but good. They do not violate the Third Commandment. Instead, they help Christians keep their word when righteousness is hard. It is an interesting argument. It is also not the reason most people will pick up this book. The second appendix, "On Usury," is.
This is where things finally get interesting, and it is the only reason this book earns three stars instead of one. Musculus defines usury as unjust profit gained at the expense of others. Not just bad loans. Not just shady interest rates. Any gain that comes from squeezing your neighbor. I could not help but think of Calvin while reading this section. Calvin argues that injustice begins when one person thinks he is more than another. That idea sits right at the center of Musculus’ argument. Usury is not just bad economics. It is unjust gain over another.
Musculus also points out something that almost feels offensive to my little Presbyterian ears. Pre-Trent Catholicism took usury seriously! Canon law had special protections against it. Banks could not simply do whatever they wanted but were limited in how they could profit from others. Of course, through some creative accounting and a loose interpretation of the law, people eventually found ways around those rules. Musculus’ point is simple. Legal does not mean permissible. Some things remain objectively sinful even when the law says its permissible.
So why read this now? Because we as a society have largely forgotten that usury is a sin.
It is easy to recognize slavery as sin. We recognize theft as sin. Most of us even recognize wage exploitation as sin. But usury slipped through the cracks of supposed progress. Usury today looks like predatory lending, absurd rent, manufactured inflation, hidden fees, sports gambling, subscription based economics, literally all of StubHub, and lotteries that prey on the poor. We call all of these normal parts of living in a free market society. Spend five seconds on LinkedIn and you will probably see them praised as clever innovations.
But the real weight of Musculus’ argument is not economic. It is pastoral. Usury is not just out there in banks and corporations. It lives much closer to home. It shows up in the quiet decisions we make when we benefit at someone else’s expense. It shows up when we accept a price we know is unfair. When we take advantage of a situation because it works in our favor. When we profit without asking who paid for it.
If Musculus is right, then usury is not just a societal sin. It is a personal one. That is a harder pill to swallow. It is easy to condemn obvious exploitation. But usury hides. We are often far too quick to justify it as an unfortunate but unavoidable feature of the free market.
Let me take a moment to say that I am generally a fan of free markets. I might even suggest Adam Smith’s invisible hand sounds a lot like the way I imagine a sovereign God might involve himself in the economic affairs of his people. But somewhere along the way, from Max Weber’s "The Protestant Ethic and the Spirit of Capitalism" to our present age, we began to baptize usury as a Christian virtue. We tell ourselves it's okay to exploit others as long as its in the name of “share holder value” and the “bottom line.” It's okay to shop from TEMU even though they literally enslave people, because I am getting a heck of a deal. It's okay to charge the artificially inflated “market price” for my rental property, even though I am profiting 10 fold and keeping a usable home off of the market because I am laying up a nest egg for myself. And we accept it as normal.
Part of that acceptance runs on a powerful myth. One day I might be rich. But even the rich have duties toward their neighbors. Wealth does not erase responsibility. A society without guardrails eventually devours itself.
Musculus pushes us even further. He reminds us that righteousness is not merely avoiding evil. It is loving your neighbor in how you live, trade, and earn. The real question is not “Did I break a rule?” It is “Did I deal justly? Did I love mercy? Did I walk humbly before God?” That changes everything!
TGC recently ran an article that said, “your bank account is not neutral.” That means, your purchases are not neutral. Your wages, your investments, your side hustles. None of it is neutral. We are either being righteous with what God has entrusted to us, or we are not. Morality does not have a middle ground.
Usury, then, is not merely a failure of economics. It is a failure of worship. When we unjustly profit at the expense of others, we do not merely break the Eighth Commandment, “You shall not steal,” or the Tenth, “You shall not covet.” In a deeper sense, we take the Lord’s name in vain. We claim to belong to a just and generous God, yet act as if provision depends on how much we can squeeze out of other people.
I watched a YouTube video recently about a business using a pawn shop style model that effectively robbed an elderly man of $200,000 while staying within the bounds of the law. The video kept using the phrase “restorative justice,” and I found myself a little uncomfortable with the word. It sounded like another academic buzzword from critical theory.
But in truth, restoration is exactly what God does. God does not merely punish sin. He takes it upon himself. He does not leave us to fend for ourselves. He gives us Christ’s righteousness. Where secular theories hope the market or the state will eventually produce justice, Scripture begins somewhere deeper. A just society requires just people. Just people come from a just God who saves sinners.
So I find myself asking uncomfortable questions. Where have I benefited from injustice? Where have I called something normal that Scripture might call sin? Where have I confused profit with blessing? For what it is worth, I still find myself agreeing, at least in part, with Adam Smith. Free markets can work. I mean, I voted for Gary Johnson in 2016 for crying out loud. But markets do not work on their own. They need guardrails. A Christian society cannot shrug at the suffering of its people and call it efficiency.There was a moment when deregulation became the buzzword of the political moment. If we deregulated banks, airlines, and business in general, the economy would supposedly correct itself. But history shows that when business is left entirely unchecked, it tends to draw more and more blood.
Left to our own devices, without the restraining hand of God, there is not a single person alive who will eventually say, “I have had enough.” The temptation to accumulate more is endless. That does not mean wealth itself is sinful. Scripture never says that. Providing for your family is good. Building something and passing it on is good. Money itself is not evil. But profiting unjustly from others is.
Somewhere along the way we replaced the American Dream with the nightmares of hustle culture. And people buy into it because they are trying to survive in a system that squeezes them from every direction. There was a time when a door to door salesman could reasonably expect to own a home and provide for a family. That world feels very far away now. In many ways we built an entire way of life on pretending usury is not a sin. We call it normal. I am not convinced it is.
March 22, 2018
Musculus provides a commentary on Psalm 15 followed by two appendices : on oaths, which answers the anabaptists; and another on usury which takes a surprisingly firm line .
September 28, 2016
A helpful and solid book by a lesser known light from the Reformation age. It includes three parts: an exposition of Psalm 15, an appendix on oaths, and a appendix on usury. I got this specifically for the appendix on usury, as I am curious about the topic. Musculus views all usury as wrong, which put him at odds with other theologians of the age. He does see some usury, particularly that which takes advantage of the poor, as worse than others.
I found the translation a bit clunky. Translation work is not my expertise. Therefore I am not sure how hard to be. But it was not as fluid to read as some other translated works.
I would recommend this book to anyone interested in either oaths or usury or curious about Musculus' theology in general. If you are looking for a commentary on Psalm 15 there are better ones out there. I would not buy it simply for that portion.
My Rating System
1 Star-Terrible book and dangerous. Burn it in the streets.
2 Stars-Really bad book, would not recommend, probably has some dangerous ideas in it or could just be so poorly written/researched that it is not worth reading. Few books I read are 1 or 2 stars because I am careful about what I read.
3 Stars-Either I disagree with it at too many points to recommend it or it is just not a good book on the subject or for the genre. Would not read it again, reference it, or recommend it. But it is not necessarily dangerous except as a time waster.
4 Stars-Solid book on the subject or for the genre. This does not mean I agree with everything in it. I would recommend this book to others and would probably read it again or reference it. Most books fall in this category because I try not to read books I don’t think will be good. There is a quite a variety here. 3.6 is pretty far from 4.5.
5 Stars-Excellent book. Classic in the genre or top of the line for the subject. I might also put a book in here that impacted me personally at the time I read it. I would highly recommend this book, even if I do not agree with all that it says. Few books fall in this category. Over time I have put less in this category.
I found the translation a bit clunky. Translation work is not my expertise. Therefore I am not sure how hard to be. But it was not as fluid to read as some other translated works.
I would recommend this book to anyone interested in either oaths or usury or curious about Musculus' theology in general. If you are looking for a commentary on Psalm 15 there are better ones out there. I would not buy it simply for that portion.
My Rating System
1 Star-Terrible book and dangerous. Burn it in the streets.
2 Stars-Really bad book, would not recommend, probably has some dangerous ideas in it or could just be so poorly written/researched that it is not worth reading. Few books I read are 1 or 2 stars because I am careful about what I read.
3 Stars-Either I disagree with it at too many points to recommend it or it is just not a good book on the subject or for the genre. Would not read it again, reference it, or recommend it. But it is not necessarily dangerous except as a time waster.
4 Stars-Solid book on the subject or for the genre. This does not mean I agree with everything in it. I would recommend this book to others and would probably read it again or reference it. Most books fall in this category because I try not to read books I don’t think will be good. There is a quite a variety here. 3.6 is pretty far from 4.5.
5 Stars-Excellent book. Classic in the genre or top of the line for the subject. I might also put a book in here that impacted me personally at the time I read it. I would highly recommend this book, even if I do not agree with all that it says. Few books fall in this category. Over time I have put less in this category.
Displaying 1 - 3 of 3 reviews