The researchers found that nonchurch friends do not provide the same benefit in terms of well-being and that other measures of religiosity -- belief in God or frequency of prayer, for example -- do not serve as a reliable predictor of a person's satisfaction with life.

"People who frequently attend religious services are more satisfied with their lives not because they have more friends overall (when compared with individuals who do not attend services) but because they have more friends in their congregations," the two researchers wrote in the American Sociological Review.

And churchgoing alone without making friends does not improve well-being, they found.

"In short, sitting alone in the pew does not enhance one's life satisfaction," Putnam and Lim wrote. "Only when one forms social networks in a congregation does religious service attendance lead to a higher level of life satisfaction."

At the summit, Gallup unveiled its latest studies on how religion affects well-being, both in the United States and worldwide.

Reviewing data from more than 676,000 participants in the Gallup-Healthways Well-Being Index interviews in 2010 and 2011, Gallup researchers found a statistically significant relationship between religiousness and well-being, after controlling for such demographic variables as age, gender, race and ethnicity, geographic location, socio-economic status, marital status and child-bearing status.

The researchers defined participants as "very religious," "moderately religious" or "nonreligious," depending on their answers to two questions -- is religion an important part of your daily life and how often do you attend your church, synagogue or mosque.

The study found that those who were considered "very religious" -- 41 percent of the population -- not only had higher well-being but were much less likely to smoke and more likely to exercise and eat five fruits and vegetables a day, said Frank Newport, Gallup's editor-in-chief and the immediate past president of the American Association for Public Opinion Research.

Those who were in the "nonreligious" category -- about 31 percent of the population -- had a higher level of well-being, however, than the 28 percent of the population that is considered "moderately religious."

"This study does not allow for a precise determination of why this might be the case," said a Gallup report on the data. "It is possible that Americans who have higher well-being are more likely to choose to be religious than those with lower well-being, or that some third variable could be driving certain segments of the U.S. population to be more religious and to have higher well-being."

The report also postulated that the "more meditative states" and faith in a higher power associated with religion have been used as ways to "lower stress, reduce depression and promote happiness" and that Christianity's emphasis on charitable acts and "positive relationships with one's neighbors" might "lead to a more positive mental outlook."

Members of the Jewish and Mormon faiths were found to have the highest well-being overall, while those with no religious identity were the lowest. Catholics scored slightly lower than Muslims on the well-being index, but higher than Protestants and other non-Catholic Christians or members of other non-Christian religions.

Paradoxically, Jews were least religious of these groups, except for those who said they had no religion. Less than 17 percent fell into the "very religious" category, while 53.5 percent of Jews were considered nonreligious.

Catholics were in the middle of the pack in terms of religious intensity, Gallup found. Less than half (44 percent) of Catholics were in the "very religious" category, compared to 73 percent of Mormons, 51 percent of Protestants and other non-Catholic Christians and 47 percent of Muslims.

Nearly a quarter of those who identified themselves as Catholics fell into the "nonreligious" category.

"The findings confirm that the strong positive relationship between religiosity and well-being that Gallup previously demonstrated holds regardless of faith," said study authors Newport, Dan Witters and Sangeeta Agrawal in their report.

But a report drawn from the Gallup World Poll by Angus Deaton, a professor of international affairs and economics at Princeton University, found that when a country's population is taken as a whole, a high level of religious involvement does not necessarily translate into better life satisfaction.

Not surprisingly, well-being was lower in poorer countries, where religiosity was higher. The countries where well-being was highest were in Scandinavia, where religious practice is the lowest.

Deaton explained the findings by citing the case of his own father, who grew up in a tough English mining village called Thurcroft, where violence was prevalent and the Methodist Church became a sanctuary where villagers could find order, rules and protection against local dysfunction.

"As the state becomes more effective and expands its safety net," there is less need for religion on a societal basis, he said. "The state substitutes for religion."