The Christian Case Against Interest: Reviving an Old Conviction

For roughly fourteen centuries, a Christian cleric who lent money at interest could be deposed from office, and a layman who did it openly could be refused communion and Christian burial. That was conciliar law rather than the private severity of a few ascetics, repeated at Nicaea in 325 and hardened at the Third Lateran Council in 1179. Then, over about three hundred years, it quietly stopped being enforced, stopped being preached, and eventually stopped being remembered.

The Christian case against interest never got formally repealed. It got abandoned by attrition. And a slice of the Biblically Responsible Investing world has started picking it back up, mostly around consumer lending rather than corporate finance. Worth understanding what the old rule actually said before deciding whether you agree with it.

What the Texts Actually Say

The scriptural material is more specific than most people expect, and it is not one flat prohibition.

The Torah sets up a two-tier rule

Exodus 22:25 addresses the lender directly: if you lend to one of my people who is poor among you, do not act as a creditor toward him and do not charge him interest. Leviticus 25:35-37 extends it, forbidding both neshekh (literally "a bite," advance-deducted interest) and tarbit (increase, interest added at repayment), and grounding the ban in the fact that God brought Israel out of Egypt. Deuteronomy 23:19-20 is the one that generates centuries of argument: no interest to your brother, but you may lend at interest to a nokri, a foreigner.

That foreigner clause is the hinge. Read one way it is a narrow commercial carve-out for cross-border trade. Read another way it proves the prohibition was covenantal ethics for insiders rather than a universal moral law about money. Christian interpreters have gone both directions, and honestly the text supports the argument on both sides.

The prophets and the Psalms treat it as a character test

Psalm 15 asks who may dwell on God's holy hill and answers, among other things, the man who does not put out his money at interest. Ezekiel 18 puts it in a list of what makes a man righteous (verse 8, does not lend at interest or take any increase) and then in the parallel list of what makes a man deserving of death (verse 13). Ezekiel is not talking about a technical banking violation. He files interest alongside idolatry, adultery and robbing the poor.

Nehemiah 5 is the case study. Returning exiles are mortgaging fields and vineyards to pay the king's tax, and their own nobles are lending against those fields and then taking the borrowers' sons and daughters as bondservants. Nehemiah's fix is restitution: give back the fields, the olive groves, and the hundredth part of the money you have exacted. The sin and the mechanism are named in the same breath.

The Gospel raises the bar rather than relaxing it

Luke 6:34-35 tells disciples to lend expecting nothing in return. There is a real translation dispute about the Greek mēden apelpizontes, which can be read as "despairing of no one" rather than "expecting nothing back." Either way, the early church read it as tightening the Old Testament rule rather than loosening it, and crucially as removing the brother-versus-foreigner distinction. Basil, Ambrose and Chrysostom all preached against interest in blunt terms. Ambrose is the one who articulated the ugly logic openly: take interest from the man you would be justified in going to war with.

The Councils and the Canon Law Trail

Doctrine here is unusually well documented, so you do not have to guess.

Nicaea's canon 17 (325) deposes clergy who take interest. Lateran III canon 25 (1179) denies manifest usurers communion and Christian burial. The Council of Vienne (1311-12) went furthest: anyone who obstinately maintains that taking usury is not a sin is to be punished as a heretic. That is about as strong as ecclesiastical language gets.

The Fifth Lateran Council in 1515 did two things at once. It approved the montes pietatis, the charitable pawn-lending institutions that charged a modest fee to cover their operating costs, which is the first structural crack. And it gave the definition that everything after it argues about: usury is gain sought from the use of a thing that is not fruitful in itself, obtained without labor, expense or risk.

Then Benedict XIV's encyclical Vix Pervenit (1745) restated the ban on charging anything beyond principal on a mutuum, a simple loan, while explicitly acknowledging that titles entirely extrinsic to the loan itself might sometimes justify a return. The 1917 Code of Canon Law then permitted legal-rate interest on loans of ecclesiastical property (canon 1543), and the 1983 Code dropped the usury vocabulary altogether. Nobody stood up and reversed Vienne. The category just got narrowed until it stopped covering anything anyone actually does.

The Mechanism: Why the Old Rule Called It Selling Time

Aquinas gives the reasoning in the Summa Theologiae (II-II, q. 78, a. 1), and understanding it matters more than memorizing the verdict.

His argument is that money is a consumable. When you use wine, you drink it, and the use cannot be separated from the thing. So selling someone wine and then separately charging them for the use of the wine is charging twice for one item. Money, in the medieval view, works the same way. Its whole function is to be spent. Charging principal back plus a fee for the use of the money is billing twice for one transfer.

Stack the Lateran V definition on top and you get the real test: is the lender bearing labor, expense or risk? A partner who shares the loss has earned a share of the gain. A lender whose return is fixed regardless of what happens to the borrower's venture has not. The scholastics allowed damnum emergens (compensation for a loss the lender actually suffered) and argued endlessly about lucrum cessans (profit the lender forwent). Those are the extrinsic titles Vix Pervenit nods at. They are exceptions that concede the principle, and the shape of the reasoning is close enough to the Islamic distinction between profit-and-loss partnership and guaranteed return that Muslim and Catholic writers on this topic frequently cite each other.

The Strongest Counterargument

The permissive case deserves to be taken seriously, because it is strong. Calvin's 1545 letter to Claude de Sachin is the pivot document in the Protestant world. His argument: the biblical texts target loans to the destitute, the Deuteronomy 23 exemption shows the ban was not a universal moral absolute, and Aquinas's sterility premise is simply wrong about capital in a commercial economy. Money lent to a merchant who buys inventory with it is productive. Calvin did not throw the doors open. He kept conditions, including no interest from the poor, no lending as a profession, and the borrower must profit at least as much as the lender. Later generations kept the permission and dropped the conditions.

The economic version is harder still. If inflation runs even three percent, a zero-interest loan repaid in five years returns meaningfully less purchasing power than was lent, which makes the "no gain beyond principal" rule a mandate for the lender to absorb a real loss. Add opportunity cost and default risk, and a fixed rate starts looking like compensation for genuine expense and risk, which is exactly what Lateran V said was permissible. Modern deposit insurance, securitization and floating rates make the medieval picture of a rich man lending to a desperate neighbor a poor description of what a bond is.

Where I think the counterargument is weakest is at the consumer end. A payday loan at the commonly cited triple-digit annualized rates, or a subprime auto loan structured so that repossession is a profit center, has very little to do with productive capital lent to a merchant and quite a lot to do with the arrangement Nehemiah broke up. Calvin's own carve-outs would exclude it.

Debt Slavery Is the Part That Never Went Abstract

The Torah's interest rules do not stand alone. They sit inside a system with the seventh-year release of debts (Deuteronomy 15:1-2), the return of ancestral land at Jubilee (Leviticus 25), and redemption rights for a relative who sold himself into service. Interest was one lever in a mechanism designed to stop debt from converting free households into permanent servitude.

That framing is why the modern BRI revival tends to focus on lending practices rather than on the existence of interest. When a lender's business model depends on a borrower never escaping the principal, on rollover fees, on refinancing churn, or on collateral seizure being more profitable than repayment, you are looking at the exact outcome the sabbatical and Jubilee provisions were built to prevent. You can hold that conviction without accepting Aquinas's sterility argument at all.

Why Standard BRI Screens Mostly Skip Interest

The honest gap sits right here. The Biblically Responsible Investing screens most Christian investors encounter are built around a familiar set of categories: abortion and abortifacients, pornography, anti-family entertainment, alcohol, tobacco, gambling, and depending on the provider, human trafficking and human rights abuses. Interest income is generally not on that list. Providers like Timothy Plan, Inspire and eVALUEator score companies on those behavioral categories, and a regional bank whose entire revenue line is net interest margin will typically pass.

Meanwhile the Islamic frameworks screen interest quantitatively. AAOIFI-derived methodology caps interest-bearing debt at roughly 30 percent of market capitalization, caps interest-bearing securities and cash similarly, and requires that impermissible income (mostly interest) stay under 5 percent of revenue with the tainted portion purified out. Nothing equivalent exists in mainstream BRI. If you compare how the frameworks handle the same balance sheet on our framework comparison page, the divergence on financials is the sharpest gap between the Islamic and Christian screens.

The revival is happening mostly outside the big BRI product lineup. Anabaptist-rooted institutions like Praxis and Everence have run community development lending at concessional rates for decades. Jubilee-style debt cancellation campaigns and church-run predatory lending reform coalitions come from the same conviction. Catholic social teaching keeps the language alive through its treatment of sovereign debt relief.

Practical Guidance

If you want to act on this rather than just admire it, a few concrete moves.

Decide first which version you hold. The strict view (any fixed return on a loan is illicit) rules out bonds, money market funds, CDs and most bank equity, and it is very hard to implement in a public portfolio. The Nehemiah view (interest is licit in principle, exploitative lending is the sin) is implementable today and is where most of the revival sits.

Then screen at the business-model level. Look at what share of a company's revenue comes from net interest margin, and separately at what share comes from fees on late payment, overdraft, rollover and repossession. A commercial bank lending to businesses looks very different from a lender whose income concentrates in penalty fees on people who cannot pay. Consumer finance, rent-to-own, subprime auto and buy-now-pay-later companies deserve line-by-line reading of the fee disclosures.

Check your own funds. A broad index fund carries a large financials weight by default, and a target-date fund holds a bond sleeve that rises as you age. Neither is visible unless you look at holdings.

Finally, if you hold the stricter view and cannot avoid incidental interest, consider the purification practice the Islamic frameworks formalize: calculate the tainted share of income and donate it, claiming no benefit. That practice is not part of standard Christian teaching, but it is a coherent way of handling money you judge you should not keep.

How FaithScreener Handles the Interest Line

Interest is the one input FaithScreener computes the same way across every framework, then interprets differently. Every screened equity gets its interest-bearing debt, its interest-bearing securities and cash, and its non-compliant income share calculated as ratios, which our methodology documentation lays out in full. Under the Islamic lens those ratios drive a pass or fail against AAOIFI-style thresholds and a purification percentage. Under the Christian BRI lens the same numbers surface as disclosure rather than an automatic disqualifier, since the BRI category set does not treat interest income as an exclusion, alongside the business-activity flags that BRI does act on.

That design means you can run a company through the screener and see the interest exposure whether or not your framework treats it as a red line. If you have concluded that the old conviction still binds, the number you need is on the page even though the default Christian verdict will not fail the stock for you.

The Bottom Line

The Christian prohibition on interest was real conciliar doctrine, defended by Nicaea, Lateran III, Vienne and Vix Pervenit, resting on a specific argument that money is sterile and a fixed return without labor, expense or risk is payment for nothing. It faded through narrowing exceptions rather than any formal reversal, and Calvin's productive-capital objection plus modern inflation math give the permissive side a genuinely strong case. What survives the counterargument intact is the Nehemiah 5 core, the objection to lending structured so the borrower cannot escape. If you remember one thing, make it that the mainstream BRI screens you are probably using do not test for interest at all, so a bank or a payday lender can pass a Christian screen while failing the Islamic one on the same balance sheet. You have to look at that number yourself.

This is educational research rather than a religious ruling or personalized investment advice, so confirm your own position with a qualified pastor, theologian or financial advisor before acting on it.