Take a look at this list of countries: Belgium, Canada, Spain, Argentina, Portugal, Brazil, France, Uruguay, Luxembourg, and Ireland. Name two things that they have in common.

They don’t share a continent, obviously. Or a language.

But in all of them, the Roman Catholic Church has more adherents, at least nominally, than any other religious denomination does.

And all of them belong to the vanguard of 20 nations that have decided to make same-sex marriage legal.

In fact, countries with a Catholic majority or plurality make up half of those where two men or two women can now wed or will soon be able to.

Ireland, obviously, is the freshest addition to the list. It’s also, in some ways, the most remarkable one. It’s the first country to approve same-sex marriage by a popular referendum. The margin wasn’t even close. About 62 percent of voters embraced marriage equality.

And they did so despite a past of great fealty to the Catholic Church’s official teachings on, for example, contraception, which was outlawed in Ireland until 1980, and abortion, which remains illegal in most circumstances.

Irish voters nonetheless rejected the Church’s formal opposition to same-sex marriage. This act of defiance was described, accurately, as an illustration of Church leaders’ loosening grip on the country.

But in falling out of line with the Vatican, Irish people are actually falling in line with their Catholic counterparts in other Western countries, including the United States.

They aren’t sloughing off their Catholicism — not exactly, not entirely. An overwhelming majority of them still identify as Catholic. But they’re incorporating religion into their lives in a manner less rooted in Rome.

We journalists too often use “the Catholic Church” as a synonym for the pope, the cardinals, and teachings that have the Vatican’s stamp of approval.

But in Europe and the Americas in particular, the Church is much more fluid than that. It harbors spiritually inclined people paying primary obeisance to their own consciences, their own senses of social justice. That impulse and tradition are as Catholic as any others.

Catholics in the United States appear to be more, not less, progressive about gay rights than Americans in general are. In an especially ambitious survey conducted over the course of 2014 by the Public Religion Research Institute, about 60 percent of Americans who called themselves Catholic said that they approved of same-sex marriage, versus about 30 percent who didn’t. The spread among all respondents was 54 to 38, and the group that clearly stood in the way of same-sex marriage wasn’t Catholics. It was evangelical Protestants.

And yet, interestingly, the qualms that certain public figures have about same-sex marriage are routinely explained — by the media, and sometimes by those people themselves — as ineluctable consequences of their Catholicism.

“We need to be stalwart supporters of traditional marriage,” Jeb Bush, who converted to Catholicism as an adult, said during a recent TV interview. “It’s at the core of the Catholic faith.”

Rick Santorum, Bobby Jindal, Chris Christie, and Marco Rubio, among others, have cited their Catholic devotion as a barrier to embracing same-sex marriage. But seldom does anyone point out that this explanation puts these men in the minority, not majority, of Catholics in the United States. Their stances win them more political favor among Baptists than among Catholics.

That’s because “Catholics” includes not just worshippers who attend Mass weekly and perhaps tilt in a more conservative direction, but also those who go less frequently and those for whom Catholicism is as much an ethnic as a religious identity.

For this large and diverse group in the United States and other Western countries, same-sex marriage has rapidly gained favor, and Catholic leaders’ expressions of protest, such as firing employees who marry same-sex partners or speak up for marriage equality, are becoming untenable.

Cognizant of that, Catholic bishops in Germany voted earlier this month to relax morality clauses in contracts with lay workers so that those who remarry after a divorce or enter into same-sex civil unions (same-sex marriage isn’t yet legal there) needn’t fear losing their jobs.

Is this a sign that in Europe and the Americas, same-sex marriage could become analogous to divorce: something that Catholic leaders technically frown upon, but don’t bother to inveigh against all that much?

I wonder, especially in light of comments by Diarmuid Martin, the archbishop of Dublin, after the Irish referendum. He noted “a growing gap between the culture of Ireland” and the Church, which, he said, “needs to take a reality check.”

He meant that its leaders do, and they can turn not just to Ireland, but to many other densely Roman Catholic countries to gauge the hearts and souls of Catholics today.