A friend of mine once described her investment account as "ethically clean". She'd chosen a Sharia-compliant fund, gone through the onboarding, understood that alcohol and conventional banking were out. She felt good about it.
A few months later, her colleague mentioned he'd just moved into a biblically responsible investing fund. They compared notes over lunch. Same major technology holdings. Same tilt toward large-cap US equities. Same rough sector weights.
They had started from entirely different moral frameworks and arrived at nearly identical portfolios.
This isn't a coincidence. It's structural.
The exclusion game and what it actually removes
Every faith-based investment framework starts with a list of things you cannot own. The specifics differ — Sharia prohibits interest-bearing instruments and businesses deriving revenue from alcohol, pork, and conventional insurance; Catholic and broader Christian screens typically exclude abortion services, contraceptives, weapons manufacturers, and gambling; Buddhist-influenced screens often add animal testing, fur, and intensive agriculture.
Those exclusion lists feel meaningfully different when you read them on a page. And in principle, they are. The reasoning behind each is theologically distinct. Sharia's prohibition on riba (interest) is about the ethics of money itself — the idea that money should not generate money without underlying productive activity. Catholic exclusions reflect a natural law tradition about the sanctity of life. They are not the same philosophy wearing different clothes.
But when you move from theology to the actual composition of a modern equity index, the exclusions produce a surprisingly similar residue.
Here is why.
The global equity market — whether you measure it by MSCI World, FTSE All-World, or a comparable broad index — is dominated by technology companies, healthcare companies, consumer giants, and industrial conglomerates. Technology alone accounts for something in the range of 20–25% of the developed-market index, depending on the year. Healthcare follows. Consumer staples. Financials.
Now apply your screens:
- Sharia screens remove most conventional banks and insurers (interest-bearing), which reduces the financials weight sharply. Everything else in the top 20 holdings mostly survives.
- Christian and Catholic screens remove weapons, gambling, and reproductive health companies. The financials weight stays. Defence-adjacent industrials shrink. Technology mostly survives.
- Socially responsible screens (the secular cousin in this space) remove fossil fuels and weapons. Technology mostly survives.
The common denominator is technology. Apple, Microsoft, NVIDIA, Alphabet, Samsung — these companies pass Sharia screens because they don't derive significant revenue from prohibited activities. They pass Christian screens for the same reason. They pass Catholic screens. They pass ESG screens. The result is that every screened fund over-weights the same cluster of global megacaps, because that cluster is where most of the market capitalisation sits, and it's also the part of the market that tends to clear every theological test.
You screen out the banks, the brewers, the defence contractors, and the tobacco companies. What you're left with is, essentially, a bet on large-cap global technology and consumer brands.
And that's the whole game.
The convergence problem — and the purification footnote
This convergence is not a scandal. It's worth understanding clearly, but it doesn't mean faith-based investing is a marketing illusion. The differentiation exists at the margins, and those margins are more meaningful than they look at first glance.
Sharia-compliant portfolios have one feature that is entirely absent from other faith-based frameworks: purification. If a company passes the primary revenue screens but earns some small percentage of income from impermissible sources — say, a tech company that offers a payment product with an interest component — the investor is expected to donate the proportional share of those earnings to charity. Purification transforms the portfolio from a static yes/no list into an ongoing ethical accounting. You own the company, but you audit it.
No other faith-based framework has an equivalent mechanism built in at this level of granularity. Catholic investing involves engagement — active pressure on companies to change behaviour — but it doesn't involve returning a fraction of your dividends to charity as a mathematical function of the company's impure revenue mix. These are genuinely different approaches, even when the underlying holdings overlap.
Catholic and Christian investing frameworks also differ in emphasis when it comes to positive screening: not just removing bad actors, but actively weighting toward companies whose governance and labour practices reflect certain values. This is a different tool. An exclusion screen draws a fence. A positive screen asks what you want inside it.
The portfolio convergence at the holdings level masks real divergence at the method level. What your faith-based framework is doing — the process by which it monitors, adjusts, engages, and accounts for your holdings — can be more distinct than the list of tickers suggests.
What a conviction-led investor should ask
If you are the kind of investor who has chosen a faith-based framework not because it was the default, but because you actually hold the conviction — you've thought about why riba troubles you, or why weapons manufacturing sits outside what you want to fund — the near-identical portfolio problem is a signal worth sitting with.
It is telling you something specific: the biggest source of differentiation in a global equity portfolio, once you apply any meaningful ethical screen, is not which faith you follow. It is which part of the market you exclude or include beyond the obvious prohibited sectors.
A Sharia-compliant fund that holds 500 equities will share, conservatively, 70–80% of its holdings with a Catholic-screened fund of similar size. The divergence happens in financials (where Sharia cuts deep and Catholic screens cut less), in healthcare (where Catholic screens are stricter on certain subsectors), and in small- and mid-cap exposure (where most faith-based funds barely venture, because screening is harder and index-building is expensive).
The small- and mid-cap gap is underappreciated. Index-hugging faith-based ETFs concentrate in large, globally recognised companies partly because those companies are heavily analysed and their revenue breakdowns are well documented. A mid-cap electronics manufacturer in Southeast Asia is harder to screen. The data is thinner. So screened funds quietly avoid it, not for theological reasons, but for operational ones. The result is a structural large-cap bias that has nothing to do with faith and everything to do with the economics of running a compliance-heavy fund.
If your conviction is genuine — if you care not just about the label on the fund but about the actual shape of your exposure — this matters. You might be paying a premium fee for a faith-aligned product that delivers large-cap US tech with three sectors removed. That might be exactly what you want. But it is worth knowing that's what you're holding.
What real alignment looks like
Real faith-aligned investing, taken seriously, is not just a screened version of the S&P 500. It is a question about where capital should flow.
A Sharia framework, followed rigorously, asks whether money is being put to work in productive, non-exploitative activity. That is a question about the nature of business, not just its sector. A Christian stewardship framework asks about the dignity of labour and the treatment of creation. A Catholic framework asks about the sanctity of life at every point in the supply chain. These are not slight adjustments to a standard portfolio — they are different theories of what capital is for.
The ETF wrapper makes these frameworks feel similar because the ETF wrapper flattens everything into a list of tickers. A tick-box screen applied to a passive index will always produce convergence, because the index itself is neutral on theology. The screen is working against the grain of the instrument.
This is why some faith-aligned investors — particularly those with long time horizons who genuinely want their portfolio to express a worldview, not just avoid a shortlist of excluded sectors — find that the off-the-shelf screened ETF is a starting point, not a destination. The destination is a portfolio that reflects the full weight of the conviction: what to include, what to exclude, how to audit ongoing exposure, and how to handle edge cases that no static screen can anticipate.
My friend with the Sharia account figured this out eventually. The portfolio was clean. The logic behind it was sound. But the portfolio itself looked like everyone else's clean portfolio, and she had started to wonder whether clean was enough — or whether she wanted something that actually looked like her values, not just the absence of the worst ones.
That question — not just what to exclude but what to build — is where faith-aligned investing gets interesting. And it is a question no static ETF screen can answer on its own.