General view of the Council Fathers in St. Peter's Basilica on Dec. 8, 1962, at the Vatican, at the end of the first session of the Second Ecumenical Council of the Vatican, or Vatican II. / Credit: AFP via Getty Images
Washington, D.C. Newsroom, Aug 15, 2025 / 12:41 pm (CNA).
An economics paper published last month on religious service attendance trends in 66 countries concluded that the implementation of reforms associated with the Second Vatican Council likely contributed to subsequent Mass attendance declines.
The working paper, "Looking Backward: Long-term Religious Service Attendance in 66 Countries," was published by the National Bureau of Economic Research (NBER) on July 21.
NBER economists delved into historical trends for religious service attendance in historically Catholic and historically Protestant countries based on 1,900 religious affiliation statistics.
According to the researchers, attendance rates declined significantly faster in historically Catholic countries than in Protestant ones in the years after Vatican II. The trend began immediately after Vatican II and was not ongoing when the council began in the early 1960s.
Beginning in 1965 and through the 2010s, monthly attendance in Catholic nations decreased by an average of 4 percentage points more than Protestant countries in every decade.
Dismissing the claim that attendance rates only went down due to broader secularizing trends globally, the report asserted: "The decline in attendance is specific to Catholicism, to which Vatican II would directly apply."
NBER researchers claim that Vatican II and subsequent reforms "profoundly affected Catholic faith and practice" and concluded the council's implementation "triggered a decline in worldwide Catholic attendance relative to that in other denominations."
"Compared to other countries, Catholic countries experienced a steady decline in the monthly adult religious service attendance rate starting immediately after Vatican II," the report found. "The effect is statistically significant."
Harvard economics professor Robert Barro, one author of the study, told CNA the findings show "a substantial reduction in attendance" in Catholic countries relative to Protestant countries.
He noted the Catholic decline culminates to "as much as 20 percentage points" worse than the Protestant decline over about four decades.
Barro said "before Vatican II, the Catholic and non-Catholic places behaved in a similar manner."
He said "there's nothing before the event" but also noted the study "cannot exclude the possibility that something else that you're not looking at happened at the same time."
The NBER report incorporates retrospective questions from the International Social Survey Program (ISSP). These surveys from 1991, 1998, 2008, and 2018 gather data about the past by asking respondents about religious service attendance from their childhoods. These surveys, according to the report, fill in data for years in which there was not polling.
"Nobody before had the long-term data," Barro said.
What might have impacted the decline in Mass attendance?
Although the report is primarily an economics paper, the researchers cite sociologists who have analyzed the implementation of Vatican II. It contends the findings are consistent with the view that the implementation "shattered the perception of an immovable, truth-holding Church."
The report cites the late sociologist Father Andrew Greeley's book "The Catholic Revolution," which attributed five major changes to the post-Vatican II Church: Mass in the local language, broader ecumenism, looser rules, internal debates on birth control, and more priests seeking laicization.
Harvard economist Rachel McCleary, who is Barro's wife and has also conducted research on the Church, told CNA she believes the implementation of the council had "a secularizing effect on the Catholic Church, which means that you're losing your brand."
"They want something that's different, that addresses their spiritual needs," she said, arguing that the implementation of the council "did the reverse; it secularized the religion."
McCleary argued that the implementation led to some internal strife with some Catholics believing the effects "went too far" and others thinking they "didn't go far enough."
Father Paul Sullins, a senior research associate at the Ruth Institute, told CNA there is a distinction between Vatican II itself and the subsequent "social effects of its implementation and reception" of the council.
He warned not to confuse the implementation with "the content or documents of the council proper."
Sullins said some Church leaders "acted in what they perceived to be 'the spirit of Vatican II,' which was often not envisioned or even justified by the council itself."
Yet disproportionate attendance decline, he noted, is "undeniable and widely documented." He added: "The Catholic decline is pretty secular (gradual, long-term), so it's probably responsive to many other cultural factors [as well]," such as disputes about the Church's ban on contraception.
"But [the implementation of] Vatican II clearly worked to accommodate the Church to the world, and so contributed to the decline — the differential decline — among Catholics," Sullins said.
For example, the council itself allowed greater use of the vernacular language but also called for preserving the use of Latin and Gregorian chant in the Mass. The council did not require priests to face the people during Mass as opposed to the traditional "ad orientem" posturing in which the priest faces away from the people. It also did not discourage kneeling while receiving Communion.
Tom Nash, a staff apologist for Catholic Answers, contended the report failed to make a clear distinction between the council itself and "the infamous 'spirit of Vatican II'" when it comes to certain subjects, such as ecumenism.
"The issue is whether the actual teachings of the council triggered this decline or whether there are other factors involved," he told CNA.
Although Vatican II avoids using the word "heretic" for Protestants and opts to use "separated brethren," Nash said "the Church didn't, in fact, promote religious indifference at the council in its teachings." He said the term "is painfully but accurately used multiple times … regarding fellow Christians … who are validly baptized."
Non-Christians, Nash said, "are our brothers and sisters in the sense that we are all made in the image and likeness of God, but we painfully are not yet one Christ."
Nash cited the council's dogmatic constitution Lumen Gentium to note Vatican II "reaffirmed the Church's definitive teaching on papal primacy in governing and teaching, which Our Lord Jesus Christ instituted in founding the Church on the rock of St. Peter."
"Vatican II also reaffirmed and elaborated further on the Church's divinely given power to teach infallibly on faith and morals," he added.
Nash noted several ways the Church could improve Mass attendance, including an increase in Eucharistic reverence, such as more options for adoration, "promoting kneeling for the reception of holy Communion," and using patens to "heighten Eucharistic awareness and reverence."
He also encouraged parishes to offer confession for five to 10 hours every week.
"When we make sacramental encounters more available with Our Lord Jesus Christ, an increase in Sunday Mass participation will follow accordingly," Nash said.
