In recent weeks, there have been a number of major news stories that have -- to one degree or another -- pivoted on the sharp doctrinal divisions among American Catholics. Think religious liberty vs. the Health and Human Services rules. Think about the case of Father Marcel Guarnizo and the Buddhist-Catholic-artist-gay-activist Barbara Johnson. In the midst of all that, the top brass at The New York Times decided to accept an extremely blunt advertisement from the Freedom From Religion Foundation that, well, urged liberal and nominal Catholics to walk out of the pews that they were rarely if ever visiting anyway.

The overarching image? Liberal Catholics, argued this advertisement, are like wives caught in abusive relationships who are afraid to try to escape. The text contains virtually every image that you would ever see in classic anti-Catholic literature. Here's a key clip from a longer version of the basic text:

You’re better than your church. So why? Why continue to attend Mass? Tithe? Why dutifully sacrifice to send your children to parochial schools so they can be brainwashed into the next generation of myrmidons (and, potentially, become the next Church victims)? For that matter, why have you put up with an institution that won’t put up with women priests, that excludes half of humanity?

No self-respecting feminist, civil libertarian or progressive should cling to the Catholic faith. As a Cafeteria Catholic, you chuck out the stale doctrine and moldy decrees of your religion, but keep patronizing the establishment that menaces public health by serving rotten offerings. Your continuing Catholic membership, as a “liberal,” casts a veneer of respectability upon an irrational sect determined to blow out the Enlightenment and threaten liberty for women worldwide.

You are an enabler. And it’s got to stop.

If you imagine you can change the church from within -- get it to lighten up on birth control, gay rights, marriage equality, embryonic stem-cell research -- you are deluding yourself. If you remain a “good Catholic,” you are doing “bad” to women’s rights. You’re kidding yourself if you think the Church is ever going to add a Doctrine of Immaculate ContraCeption.

Some were shocked, shocked to see the Times leadership publish this ad and wondered if the nation's most prestigious newspaper would accept a similar item that, well, urged progressive or moderate Muslims to flee their ancient and dangerous faith. Sure enough, one of the usual suspects quickly produced an advertisement that, in terms of images and rhetoric, was a line-by-line tribute and/or satire of the anti-Catholic screed. Click here to see it.

To no one's shock, this anti-Muslim screed was rejected by Times executives.

(Cue: audible yawn) All of this was highly predictable, of course.

However, I thought there was an interesting subject lurking just below the surface of these boiling waters. Here's the key question: Why DO so many doctrinally liberal people remain members of the Catholic Church? Why don't they do the logical thing and join, oh, a visually Catholic Episcopal parish down the block? I once put that question to Andrew Sullivan in an online exchange and there was immediate silence on the other side of that exchange in cyberspace.

At the same time, statistics produced by the Pew Forum on Religion and Public Life have made it clear that millions of people are leaving Catholicism -- roughly four people headed out the Catholic doors for every one who comes in through conversion. The bottom line: One in 10 American adults is an ex-Catholic, of one form or another. Many simply join the masses of unchurched Americans. Many head to conservative churches and a few head into liberal Protestantism. Click here to see the specifics.

While surfing through some reactions to the anti-Catholic ad in the Times, I bumped into some America commentary by theologian Tom Beaudoin, who teaches at the Jesuit-run Fordham University in New York City. He is currently doing research into "deconversions" among what many call the "secular Catholics" on the doctrinal left.

Pay close attention:

Whatever one thinks of this ad, it seems to mark a particular moment in the unfolding history of the Catholic Church in the United States. That a full-page ad in one of the most influential newspapers in the country would ask members of a major religious group to walk away from that group is an extraordinary occurrence.

I hope that before people take sides pro or con on the ad, before the tendency to separate into "evil vs. good" or "good vs. evil" here, we might be able to take this opportunity for some serious thinking, and ask: What is happening with religion in general and Catholicism in particular today that would make such a moment possible?

The ad trades on the newly widespread awareness that Catholicism is shedding adherents: that most Catholics live on the "lower" end between moderate and marginal affiliation, instead of high affiliation, and that a great many are actively disaffiliating. It trades on the widely understood distance between most Catholics' beliefs and practices and official teaching on certain matters. Most important, as far as I can tell, is its remarkably confident appeal to a kind of personal agency that would make Catholics, who so often see religion as something akin to an ethnicity, walk away from it.

Whatever you think of the Freedom From Religion Foundation advertisement, and whatever you think of Fordham, the Jesuits and what not, the numbers indicate that there is a huge story looming over these debates (and I'm not talking about the wisdom of ad policies at the Times).

Once again, we are dealing with the myth that there is one body of Catholics in America with one set of beliefs. Truly, the spirits that drive the various camps within American Catholicism are legion.

Beaudoin responded to my emails and discussed what he sees happening on the Catholic left. That conversation became the hook for my Scripps Howard News Service column this week and then the weekly GetReligion "Crossroads" podcast. Here's a bite or two of what the Fordham theologian had to say:

"Secular Catholics are people who were baptized as Catholics, but they find it impossible to make Catholicism the center of (their) lives, by which I mean Catholicism as defined by the official teachings of the church," said Beaudoin. For these believers, there are "things that they learned about faith from Catholicism. Then there are things they learned from their jobs, from school experiences, from their music and from their favorite movies.

"They are hybrid believers and their faith comes from all over the place."

And what about those Pew Forum numbers?

In the end, it's impossible to ignore this mass of "secular Catholics" because it's such a large chunk of today's church, he said. In some parts of America, various kinds of "secular Catholics" now constitute a clear majority, while those who affirm traditional dogmas and doctrines are a minority.

Some of these "secular Catholics" eventually leave the church. Others choose to remain on membership rolls, on their own terms, because they find it hard to walk away, said Beaudoin. After all, there are parts of Catholicism that they affirm and they know they can ignore the parts that they reject. They have changed the church for themselves.

From his perspective, Beaudoin said it's important to believe that this trend is "not the result of lethargy, laziness, relativism, heresy or apostasy. ... There will be Catholics who insist on saying that these secular Catholics are falling away from traditional Catholic norms. But I think it would be more helpful to talk about them not as having fallen away from the Catholic faith, but as having created new, evolving spiritual lives for themselves."

That sound you hear is traditional Catholics screaming in protest.

However, think this over. If roughly 3 to 5 percent of American Catholics are going to confession on a regular or even occasional basis, then how many Catholics are left who are actually attempting to live according to the teachings -- most of the teachings, let's say -- of their faith?

I remain convinced that it's impossible to write about Catholic life today without taking this into account in the vast majority of news stories and columns.

Just saying. Enjoy the podcast.