Meet the "Nominals" people who claim a religious identity but may live it in name only.
They're proud but not practicing Catholics. They're Protestants who don't think Jesus is essential to their salvation.
And they're Jews who say they belong to the tribe by way of ancestry or culture, not religion. Indeed, many miss the most fundamental divide between Judaism and Christianity: The Pew survey found 34 percent of Jews say it's OK to see Jesus as the Messiah and still call themselves Jewish.
"They are not saying Judaism can allow belief in Jesus. They are saying if you are born a Jew, reared as Jewish and convert to Christianity, I still consider you a Jew," said Alan Cooperman, deputy director of the Pew Research Center's Religion & Public Life Project, and a co-author of the Jewish study.
Catholic researchers see similar expressions of team loyalty melded with theological confusion.
Sacraments Today, a 2008 study by Georgetown University's Center for Applied Research in the Apostolate, found most Catholics (77 percent) are proud to be Catholic but:
• Only 55 percent say they are practicing their faith.
• Most say they can be good Catholics without going to weekly Mass (68 percent)
• Helping the poor and needy is a moral obligation for most (68 percent) but fewer people (61 percent) see the sacraments as essential.
• Less than half of Catholics (43 percent) look to the pope and bishops when they make moral choices.
Each generation's views on sacraments, Mass, and moral life also are less tied to Catholicism than their parents'. Only half of the so-called "millennials" (born after 1983) say they're "proud to be Catholic."
When CARA tallies the number of U.S. Catholics, it lists 66.8 million counted by the church, but 78.2 million according to surveys that ask people their religious identity.
Protestants, too, stray from core Christian teaching while clinging to the Christian label.
"'Survey Christians' are often people who feel guilty saying they are not as religious as their parents," said Ed Stetzer, president of LifeWay Research. "They don't want to say 'atheist' since that's way too far but they are not really 'committed,' so they just say 'Christian' since it is the default category from their heritage."
That lack of doctrinal knowledge is especially apparent when researchers cut to the theological core: questions of salvation.
In a 2011 LifeWay survey of pastors and people who attend Protestant churches, one in four churchgoers (26 percent) agreed that "If a person is sincerely seeking God, he/she can obtain eternal life through religions other than Christianity."
This is also particularly true among the young. A separate LifeWay study of 1,200 young adults under age 30 found:
• Nearly three in four (72 percent) call themselves "more spiritual than religious."
• More than two in three say they rarely or never pray with others, attend worship services, or read the Bible or other sacred texts.
• More than one in four (28 percent) said God is "just a concept," and four in 10 said the devil is merely a symbol.
• Only half said that "Believing in Jesus Christ is the only way to get to heaven."
Thom Rainer, the president of LifeWay Christian Resources who cited the research in his book on these 18-to-29-year-old millennials, called the Nominals "mushy Christians."
"Most," he said, "are just indifferent."
Still, Nominals care enough to choose some kind of label to identify, however thinly, with a religious tradition. Put another way, Nominals are not synonymous with the "Nones," the one in five Americans who claim no religious identification.
Yet both groups may share a characteristic: They are unlikely to age into religious practice beyond personal prayer, said author and scholar Phyllis Tickle. She is working on a new book about the growing closeness of Jewish and Christian expression in America.
"The old saw is that after they married and had children, people would come back to organized faith. It is not true now. People under 40 are not returning to their inherited church," she said.
In her studies on contemporary Christianity, she sees it morphing from "inherited, hierarchical, location-based (churched) faith" toward forms that discard those strictures.
Believers today are still interested in a communal expression of faith. They just want a more "nimble" religion, she said. She's also optimistic, saying, "We are in pretty good shape as believers."
Another scholar, Diana Butler Bass, author of "Christianity After Religion," has a slightly different forecast.
"I suspect that many Nominals will move toward None, while a smaller percentage will embrace their inherited faiths in more personal, experiential ways," said Bass. "Generally, being part of a faith tradition 'in name only' will be increasingly hard to maintain as society grows more accepting of people who have no religious ties."