I believe it was Joanna Brooks who first formulated the idea that “excommunication is a 19th-century solution to a 21st-century problem.” It bears the marks of her elegant, intelligent phrase-making.
Since it was first uttered, this idea has fed a swelling criticism of the practice of excommunication, following from the high-profile disciplinary action against Kate Kelly and now John Dehlin. This particular criticism is separate from — though often prompted by — the specifics of the Dehlin and Kelly cases: it’s a denunciation of the practice in general, either for apostasy or for any transgression. To expel a dissident from a community is “medieval, punishing, barbaric,” as Dehlin put it in his recent Radio West interview, a throwback to the brutal religious ideology that motivated the Inquisition.
In turn, this criticism has prompted several defenses of the practice’s sociological utility and spiritual legitimacy. It’s a complicated question, and I respect voices on both sides. As with many issues, I hesitate somewhere in the middle.
Today I just want to make a narrow point about excommunication’s meaning in the 21st century, apart from the question of its legitimacy in general or its justification in the Dehlin case. Is it really the case that excommunication is an atavistic relic from a brutal past, one that has no place in the present?
It’s easy to see why the idea resonates. Excommunication from a religious community for apostasy strips an individual, at least temporarily, of her citizenship in the group. It demarcates limits to acceptable speech and action and underscores the authority of the ecclesiastical hierarchy over the individual. These effects challenge some of the central values of Enlightenment modernity, values like universal rights, individual self-determination, and tolerance. In this sense, excommunication — like many other religious practices — does indeed bear the imprint of religion’s pre-modern character.
But implicit in this argument is the sense that the Church is an institution of overweening power over the life of the individual. This notion is indeed an atavistic throwback from a medieval past in which the Church wielded unrivaled structural, political, financial, and suasive power: the Church that could consign a Galileo to house arrest, or condemn a Michael Servetus to death at the stake.
While the present-day Church does indeed continue to control large financial resources, its structural, political and suasive power in society is massively, devastatingly depleted by the twin dynamos of state and science. Its structural power has been almost entirely given over to the state’s “monopoly on force,” its suasive power to rationality’s near-monopoly on knowledge. The most salient feature of the Church in modernity is its weakness, both in society at large and over the lives of individuals. 
We see this reality reflected, in fact, in the current debates over excommunication: many people grant the validity of excommunication only in cases when it functions merely to echo and reiterate the prior authority of the state, as in cases of criminal conduct. It is only when the Church attempts to censure conduct that is permitted by state or science, when the Church wants to discipline a member for perfectly legal ecclesiastical disobedience, say, or for promoting heretical but respectably rational ideas — that is, when the Church attempts to exercise authority independent of the prior authority of state and science — that excommunication is most vigorously contested.
Let me make one thing perfectly clear: I think this is a good thing. I am a grateful subject of modernity, and I think the Enlightenment has, overall though definitely not in every case, led to human flourishing on a marvelous scale. Nor is this a lament for religion: the category of weakness has great moral power, especially within Christianity, and the Church can continue to witness holiness and condemn sin from a position of weakness.
But the Church’s present-day weakness, compared to its vast power in the past, materially changes the character of excommunication in the 21st century, because the Church itself has materially changed. The only form of authority left to the Church is, precisely, ecclesiastical authority over its members. If the Church is to act structurally in the world in any way, ecclesiastical discipline is one of the few actions it may take. In this sense, excommunication can be seen as a quintessentially 21st century response, because it reflects the Church’s vastly narrowed scope of authority.
Now, many, many objections to excommunication as a practice remain: from the pragmatic observation that high-profile excommunications are a PR disaster for the Church, to the spiritual lament that excommunication wounds the body of Christ. I find some of these objections persuasive, and some of them un-. And, of course, all of these questions are separate from the particulars of Dehlin’s case, whether or not his conduct merited excommunication and what that means. I’d rather not hash these questions out again in the comments; these conversations are ongoing elsewhere, including in Rachel’s post below, and that’s how I’d prefer it to stay.
The narrow point of (what turned out to be) this long-ish post is simply to complicate the oft-repeated notion that excommunication is old-fashioned and obsolete. On the contrary, the Church’s contested use of excommunication reflects the contours of our ongoing 21st century negotiation for social authority. The Church has lost much and is losing more. It may be that its exercise of ecclesiastical authority comes at the expense of its moral suasive power. But lets acknowledge that excommunication and related forms of ecclesiastical authority are pretty much all that remain in the 21st century.
 I’m using Church generically here, to refer to all Christian ecclesiastical bodies, from Catholic to Mormon. I think the point I’m making can be applied to all collectively, or to any individual case.
 This is not a claim, of course, that churches are entirely powerless: they continue to have a measure of cultural influence, and to guide the lives of their parishioners to some degree. But it’s honestly a pretty small degree. Just look at the home teaching numbers!
 It has many available rhetorical avenues of action, of course, but part of what I’m arguing is that the Church’s rhetorical power is vastly diminished and likely to have a relatively small effect.