While Catholics make up a quarter of the worshippers in America each week, they are only a tenth of those who attend small groups, Sunday School and volunteer in the church, a new report shows.
The most involved believers, meanwhile, are Protestants associated with an evangelical denomination, the Barna Group found.
The research group, based in Ventura, Calif., explored Americans who are active believers, particularly through group activities such as church attendance, small groups, Sunday School, volunteering and house churches.
Those who attend a church that has an attendance of 500 or more are among the most likely to participate in small groups, house churches and volunteer activities. Americans in the South make up half the nation's small group attenders – who meet regularly for Bible study, prayer or Christian fellowship – and a majority of Sunday School attenders.
Women, older adults and married Americans drive most "group faith" participation. Still, 44 percent of weekly churchgoers are aged 18 to 44.
"There certainly is a dominant demographic faith profile of Christians in the nation," said David Kinnaman, president of the Barna Group, in the report. "The typical profile of an involved Christian is a married woman in her early fifties."
Married persons make up two-thirds of those who attend church, go to small groups and participate in Sunday School. Also, nearly seven in 10 church volunteers are married.
Those who have never been married make up less than one-fifth of active worshippers.
Singles, however, are just as likely as married adults to be involved in a house church, which the Barna Group defines as an independent meeting that is self-governed and not part of a typical church.
Active churchgoers, small group attenders and volunteers are likely to be either politically conservative or moderate. A quarter of house church attenders, however, are political liberals.
Interestingly, the report points out, those associated with a mainline denomination represented an above-average percentage of house church participants and church volunteers.
African-Americans were found to be more engaged in group activities than white believers, accounting for 27 percent of small group participants and 30 percent of house church attenders.
The data is based on 10 nationwide studies, each with at least 1,000 interviews, conducted during the last 24 months.