Affinity groups are the new Homogeneous Unit Principle.

Sep 14, 2026

TL;DR: Mainline Protestants rejected the Homogeneous Unit Principle because churches shouldn’t simply reproduce the divisions and similarities already present in society. But when we build new churches around shared affinities—hobbies, identities, class, or politics—I argue we may be doing much the same thing under a different name. The church should create relationships that affinity alone cannot explain.

Former Disciples of Christ missionary and missiologist Donald McGavran became famous—and infamous, especially within more progressive Mainline Protestant spaces—for his “Homogeneous Unit Principle.”

Basically, McGavran argued that church leaders should focus on building churches through homogeneous units—groupings of people whose shared language, culture, and values make it easier for the gospel to spread through communities.

While this philosophy became widely influential within Evangelicalism, McGavran and his methods receive nary a mention in many Mainline seminaries—even those within his (and my own) Disciples of Christ tradition.

But I’ve increasingly wondered:

What if, despite rejecting the implications of McGavran’s framework, progressive Mainline Protestants are repeating some of its most problematic elements—only under a different name?

My argument is thus:

Affinity groups are the new Homogeneous Unit Principle.

To be clear from the outset, my concern isn’t with affinity groups within churches. It’s with affinity becoming the basis for forming churches.

Because if Mainline Protestants believe something is ecclesiologically problematic about intentionally building churches around people who are already alike, changing the category of similarity from race or ethnicity to interests, identities, experiences, class, or politics doesn’t necessarily solve the underlying problem.

McGavran’s Complicated Legacy

I’ve always been intrigued by the legacy of Donald McGavran, and especially his Homogeneous Unit Principle, which came to dominate the so-called “church growth movement” that was highly influential within much of Evangelicalism beginning in the latter half of the twentieth century.

McGavran was a third-generation missionary to India for the Disciples of Christ who eventually established the Institute for Church Growth at Northwest Christian College in Eugene, Oregon. Four years later, McGavran and his colleague Alan R. Tippett moved to Pasadena, California, where they launched the School of World Mission at Fuller Theological Seminary. From there, McGavran’s ideas became enormously influential within the emerging church-growth movement.1

In the June 2026 edition of The Christian Century, Francisco Herrera wrote an intriguing piece on the “complicated legacy” of McGavran, asking how someone whose life was “full to bursting with intercultural adaptation and anti-racist struggle” eventually became “the darling of White segregationist Christians.” Herrera offers a nuanced portrait I appreciated.2

Upon his family’s return to Indianapolis in 1958, for instance, McGavran boldly chose to join a Black church and wrote an “open letter to the 49 White DOC churches in the city, lambasting their total segregation from the city’s two Black churches.”

More, Herrera notes:

“He also wrote in full support of then nascent Black theology in his fascinating work The Clash Between Christianity and Cultures, published in 1974. He agreed that Black theology rightly denounced ‘Caucasian Christianity’ and its ‘mixture of affluence, white dominance, inherited privilege, [and] sex standards’ as flawed. He also praised ‘black idiom and thought forms’ for how they motivated in Black churches ‘a desire to live justly and to oppose oppression,’ perspectives perfectly concordant with the Bible which needed to be taken seriously.”

Herrera is considerably less charitable toward McGavran’s famous Understanding Church Growth, which he calls “bigotry-enabling” and accuses of “leavening the reactionary politics of the anti–civil rights movement.” Herrera quotes the dissertation of Jesse Nathaniel Curtis, who argues that McGavran’s ideas:

“gave white evangelicals theological justification and cultural analysis to recast their segregated churches and ongoing appeals to white identity as faithful evangelism rather than racism.”

That’s certainly difficult to ignore. I’m not a church historian, so I’m hesitant to offer much resistance to that historical assessment. And Herrera himself doesn’t reduce McGavran to a simple villain. Instead, he describes him as:

“a classic case of the good kid falling in with the wrong crowd. Worn out after persisting through decades of mainline indifference to his evangelistic ideas, and maybe even slightly humiliated, his persistence may well have eagerly warped into pride, a pride that sealed his ears against all dissension and insisted that he was right.”3

Herrera ultimately adds that “despite evangelism’s bad reputation, we still must share the gospel.”

I wholeheartedly agree.

While I think Herrera makes a bit of a leap connecting McGavran’s ideas all the way to those storming the Capitol on January 6, I also think McGavran would have been well served to take seriously the criticisms regarding the potential consequences of his framework—or at least the ways it was being put into practice within White American churches.

One particularly important distinction for McGavran Herrera points out was between “discipling” and “perfecting.”

“Perfecting” was where the “bringing about of an ethical change in the discipled group” would lead toward “holy living,” including commitments to “social, racial and political justice.”

The problem is that, in practice, this part often never got implemented in many White American churches.

Again, I appreciate Herrera’s nuance:

“This makes sense: some changes in the heart take time and should be made neither a requirement nor an obstacle to baptism.”

But Herrera is also right to worry that an “‘eagerness for quantitative growth’” can allow churches to sidestep the ethical dimensions of Christian life:

“Jesus never intended that after we profess to love God, our obedience to the command to love our neighbors should be postponed to a later, more convenient time. They must go together.”

I might quibble somewhat with Herrera here. I want to trust the indwelling presence of the Holy Spirit and the proclamation of the Word to move even young disciples toward greater Christ-likeness.

But I certainly agree with his broader point: an eagerness for church growth can tempt us to accommodate existing social divisions rather than allow the gospel to challenge them.

And this is where I think McGavran’s complicated legacy suddenly becomes remarkably contemporary.

Because the sociology behind the Homogeneous Unit Principle hasn’t disappeared.

People still find it easier to gather with people who are already like themselves.

The question is whether the church should organize itself around that reality.

Affinity by Another Name?

And it’s for these very same reasons that I find myself increasingly uneasy with the idea of elevating “affinity groups” as a sociological organizing principle for new churches—especially within progressive and Mainline Protestant Christian spaces.

To begin, what do I even mean by “affinity groups”?

In an interview with Luke Edwards titled “Lessons from the Fresh Expressions Movement” from the Lewis Center for Church Leadership, it is noted that these new “communities form around particular interests, activities, or affinities.”4

Edwards offers some examples of what this might look like:

“a golfing group… group that goes out on a lake to paddleboard and to meditate… a group for older adults…”

To be sure, these aren’t meant to be simply social clubs. The groups are spiritually focused; Edwards explains that leaders intentionally:

“introduce spiritual conversations to these groups. They pray together. They seek to be a new form of church together.”

And I want to be careful here. My concern isn’t with Christians golfing together or paddleboarding together or older adults gathering with other older adults. Churches have always had smaller groups organized around shared interests, identities, ages, and experiences. I co-lead a parents of teenagers small-group.

My concern is what happens when affinity moves from being a group within the church to becoming the organizing principle for the church.

Because using different words—perhaps McGavran’s words—we might say these are very homogeneous groups.

A golfing group is a homogeneous unit.

A stand-up paddleboarding group is a homogeneous unit.

A group organized specifically for older adults is, at least in one important sense, a homogeneous unit.

The terminology has changed. But has the underlying sociology?

McGavran recognized something that remains obviously true: people find it easier to form relationships with people with whom they already share something significant.

Affinity-based models begin from essentially the same observation.

And there are obvious practical advantages to doing so. I recently invited my un-churched brother-in-law to another small-group I’m a part of because he fits the group—a bunch of software engineers and techies—better than I do.

But that was precisely the practical appeal of McGavran’s principle too.

Which raises the question I think proponents of affinity-based church formation need to answer:

What makes organizing a church around a shared affinity ecclesiologically different from organizing one around a homogeneous unit?

I may be wrong—but I don’t think there is much of a difference—and simply calling one an “affinity” and the other a “homogeneous unit” certainly doesn’t establish the theological distinction.

And this matters because Mainline Protestants have largely rejected the Homogeneous Unit Principle not because its sociology was necessarily wrong, but because they saw what happens when that sociology becomes an organizing principle for Christian community.

People naturally gather with people like themselves.

But should the church?

The Sociology Is the Same

This concern becomes more significant when we consider which affinities actually form communities.

It’s no secret that Mainline Protestant denominations are in something of a death spiral, with some denominations like the ELCA projected to become virtually nonexistent in the coming decades, according to Dwight Zscheile.5

As a result, Mainline Protestant leaders have spent much of the last decade-plus desperately looking for methods of innovation and opportunities for growth. Andrew Root has written extensively about the dangers of this impulse in books like The Church After Innovation and Churches and the Crisis of Decline.

And I worry that Mainline leaders may be attracted to affinity-based models for essentially the same reason Evangelical leaders were attracted to McGavran’s Homogeneous Unit Principle:

Growth.

Again, the sociology works.

People are more likely to gather around things they already enjoy, people they already understand, and communities where they already feel comfortable.

But affinities aren’t socially neutral.

It’s also no secret that church attendance is increasingly skewing toward higher-income and more highly educated people. And this makes examples like golfing and stand-up paddleboarding particularly interesting.

Golfing and paddleboarding aren’t inherently upper-class activities. But they do require some combination of disposable income, equipment, transportation, leisure time, and access.

And increasingly, having discretionary time and disposable income is itself a luxury.

So you can create a community that never says, “Lower-income people aren’t welcome here,” while nevertheless organizing it around an activity that disproportionately attracts people of a particular socioeconomic class.

Nobody has been intentionally excluded—but the affinity itself has already done some of the sorting.

And isn’t that precisely what should make Mainline Protestants uncomfortable?

Remember Herrera’s central criticism of McGavran’s Homogeneous Unit Principle? It allowed existing social divisions to determine the picture of Christian community. Rather than challenging those divisions, churches could simply build around them—then conveniently forget to move beyond them.

My point is that affinity-based ecclesiology risks doing something remarkably similar.

Sure, the categories may be different; instead of explicitly organizing around race, ethnicity, or language, we organize around hobbies, interests, or identities.

But the sociology is the same: people who are already alike find one another, and then we build Christian community around their existing similarity.

This doesn’t mean affinity can never be useful. Shared interests can provide wonderful entry points into relationships. Again, see my own examples above.

The question is what happens next.

Does affinity become a doorway through which people enter a much larger and more complicated Christian community?

Or does affinity itself determine who the Christian community becomes? Does it ever move people beyond “golf church?”

Because if it doesn’t, we may have changed the language without changing the underlying ecclesiology; McGavran’s fatal flaw remains.

When Affinity Becomes Ecclesiology

And this brings me to what I think is the more obvious—and potentially more consequential—form of affinity within progressive Mainline Christianity: politics.

We are increasingly seeing progressive Mainline churches turn toward political activism as a primary driver of congregational life and discipleship.

My own denomination—the same denomination as the late Donald McGavran—recently introduced, from it’s New Church Ministry, what it calls “Disciples Movement Initiators” focused on:

“Contemplative Action, Prophetic Advocacy and Faith-Rooted Organizing.”

To be clear, I am NOT arguing that churches shouldn’t ever engage in political advocacy, resist injustice, or organize around issues that impact their communities.6

The question is what happens when those commitments become the primary basis around which Christian community itself is organized.

With the ever-increasing political polarization within our nation, sacralizing political action as the ultimate expression of discipleship and faithful Christian living offers some obvious—and perhaps immediate—returns.7

One’s existing political passions can be “neatly” grafted onto Christian action.

As Dwight Zscheile and Blair Pogue note:

“Political activism became in subsequent decades for some churches on the theological left a primary way to discover energy, purpose, and identity in an increasingly secular culture.”8

The political conveniently becomes both deeply spiritual and faithful. Political partisanship become acts of piety.

But if affinity is already capable of sorting us by socioeconomic class, political affinity can sort us even more efficiently.

This is where I find myself returning to McGavran.

One of the central criticisms of the Homogeneous Unit Principle is that it allowed White Christians, in particular, to build churches around people who already looked, talked, thought, and lived like themselves—and then call the resulting community church.

But couldn’t political affinity accomplish essentially the same thing?

Consider a Christian community explicitly organized around “prophetic advocacy” or a “study group to peel back colonial layers.”

Again, I am NOT against resisting racism or colonialism.

But I do wonder: Who is likely to show up?

And perhaps more importantly: Who would feel that they could belong?

With my own “Disciples Next” framework, I can’t help but wonder how much a MAGA-supporting Trump voter would actually be welcomed into the fold.

My guess? Not much.

And to be clear, I could reverse the example. We should ask the same question of a conservative Evangelical church whose identity has become intertwined with Republican politics:

Could a progressive Democrat actually belong there?

Not simply visit, not remain silent about their commitments, but actually belong.9

A quick aside here to say that the inherent problem of the sacralizing of politics is that who we vote for—not our faith and practices—become the true test of fellowship. Whereas, in past generations, congregants might vote different but join together in worship and commitment to Jesus Christ. Now our politics, not our beliefs, is often the true test of fellowship.

This comes back to where I disagree slightly with Herrera. I want to trust the power of the gospel to transform hearts and minds. And it’s for this same reason that I get nervous when the gospel essentially gets translated into advocating for a predetermined set of progressive—or conservative—political policies.

Because if McGavran’s Homogeneous Unit Principle can be criticized for letting White Christians off the hook—for allowing them to remain comfortably surrounded by people like themselves—doesn’t organizing Christian community around political affinity risk doing the same thing?

We may even tell ourselves that our particular affinity is different because ours is morally correct and “justice-seeking”

But presumably the people within every homogeneous group have reasons for believing their boundaries are justified.

And that’s where affinity stops simply being a useful tool for gathering people and starts becoming something more consequential.

Affinity becomes ecclesiology.

The community is no longer simply using a shared interest or concern to build relationships. The shared interest, identity, or ideology begins determining who the community is—and perhaps who can belong to it.

At that point, I think Mainline Protestants need to ask ourselves an uncomfortable question:

Have we actually rejected McGavran’s Homogeneous Unit Principle—or have we simply changed which homogeneous units we consider acceptable?

A Community Affinity Cannot Explain

This brings me back to what I think is the fundamental problem with the Homogeneous Unit Principle—and why I’m increasingly uneasy around the idea of affinity becoming an organizing principle for church.

Mainline Protestants have largely rejected the Homogeneous Unit Principle because a church organized around racial, ethnic, or socioeconomic similarity fails to fully embody the reconciling character of the gospel. Yet some contemporary approaches to church formation increasingly organize Christian community around affinity—shared interests, identities, experiences—and especially politics.

The categories have changed, but has the ecclesiology?

Again, I’m not arguing that affinity itself is bad. Affinity is perfectly normal. Of course golfers like spending time with other golfers. Young parents want to know other young parents. People experiencing similar struggles benefit from relationships with people who understand those struggles.

Affinity can even provide an important doorway into Christian community.

But I don not think affinity is enough as the organizing principle of a church.

Because the church—or at least the gospel that the church proclaims—should be capable of creating relationships that affinity alone cannot explain.

A golfing group doesn’t need Jesus to explain why golfers gather.

A progressive advocacy organization doesn’t need Jesus to explain why progressive activists gather.

A conservative political organization doesn’t need Jesus to explain why conservatives gather.

But what about a community where people who would otherwise have little reason to associate with one another gather around the same table?

Rich and poor.

Black and White.

Republican and Democrat.

People with different interests, lifestyles, experiences, and backgrounds.

People who might never have chosen one another, yet somehow learn to worship together, bear one another’s burdens, forgive one another, and call one another sisters and brothers.

We should want to know how and why this has happened.

And perhaps this is where my trust in the transforming power of the gospel becomes especially important.

Christian community isn’t simply supposed to affirm the affinities we already possess.10 Through the presence and activity of God, it should also transform us—including our relationships with people we might never otherwise have encountered, much less loved. Isn’t that what was so revolutionary about the early church? Jew and Greek, slave and free, rich and poor?

This is ultimately why I remain uncomfortable with affinity becoming ecclesiology.

If the affinity is the organizing principle—what’s to say the church will ever move beyond that affinity? In fact, McGavran’s legacy suggests it will not.

Said differently, if the church simply gathers people who already look alike, earn similar incomes, enjoy the same activities, share the same experiences, and of couse, vote alike—then the church risks becoming another expression of the social sorting already happening everywhere else in American life.

And SURELY we believe the gospel of Jesus calls us to more than simply that.

So perhaps the question Mainline Protestants should ask isn’t simply whether affinity-based communities are effective at gathering people.

McGavran already taught us that homogeneity can be effective.

The more important question is what kind of people our ecclesiology is forming us to become.

If we believe something important happens when rich and poor, Black and White, young and old worship together, why wouldn’t we also believe something important happens when people without shared interests, lifestyles, politics, or experiences are formed into community together?

Maybe the church is most recognizably the church not when it gathers people who naturally belong together, but when Christ creates belonging among people who otherwise wouldn’t.

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