There are but three certainties in American life: death, taxes and fibbing about how often you go to church. That last item comes via a new Public Religion Research Institute survey (brilliantly titled "I Know What You Did Last Sunday"), which found that Americans significantly overstate their church attendance to pollsters.

Most polling happens via interviews over the phone, and when we talk to complete strangers we have a tendency to tell them what we think they want to hear. Pollsters have long suspected that this dynamic has been in play with measures of religiosity in the United States, so PRRI decided to test it out. They administered the same survey questions to two groups of people: one group was asked via a traditional telephone survey, while another took the survey online.

Less than one-third of phone respondents (30 percent) admitted to attending religious services seldom or never. But online, freed from the normative pressures of interacting with another human being, 43 percent of respondents said they seldom or never went to church. Similarly, online respondents were less likely to say they went to church weekly or occasionally than were phone respondents.

These findings hold true across all religious groups. Catholics were the most likely to overstate their church attendance for a phone interviewer: Only 15 percent told a phone interviewer that they seldom or never attended church, but online more than 30 percent of Catholics admitted they rarely went to church. Even the unaffiliated -- those who say they belong to no church -- exaggerated their religious attendance for phone interviewers.

While the number of religiously unaffiliated Americans has risen dramatically in recent years, measures like belief in God and church attendance have appeared remarkably stable. Researchers have hypothesized that people were turning away from religious institutions and taking more of a "cafeteria approach" to belief. Michael Wear, a former adviser to President Obama, has defined this as the "notion of 'picking and choosing' what one wants to believe and follow from religious traditions while ignoring the rest."

But these poll findings suggest that many more people are simply not going to the cafeteria at all. "This is consistent with what we see in the rise of non-affiliation," co-author Dan Cox said. "It's about more than a rejection of institutions."

When it comes to measures like church attendance and belief in God, Cox doesn't think we're going to turn into Western Europe any time soon. But these findings do show that we are becoming a more secular nation than previously assumed.