Hypocrisy of professed Christians is the leading cause of people doubting the Christian faith, according to a Barna Group report published March 1.

U.S. adults were surveyed about doubts they have regarding their faith tradition and about doubts they have toward Christian faith.

A majority of all demographics who affiliated with a faith tradition expressed that they had doubts about their faith frequently, occasionally or sometimes: 52% of all U.S. adults, 53% of all Christians, and 54% of other faith traditions.

Less than half (45%) of “nones” – people who do not affiliate with a religious faith – said they have doubts frequently, occasionally or sometimes.

Respondents were then presented with 14 possible causes that might make them “doubt Christian beliefs,” and they were asked to indicate all applicable reasons. “The hypocrisy of religious people” was the most common response by “nones” (42%) and by non-Christians (24%), and it was the second most-common response of Christians (22%).

Human suffering (23%) was the most common cause for U.S. Christians, while the second-most common cause for “nones” was science (31%) and for non-Christians it was human suffering (21%).

U.S. Protestant pastors were generally attuned to the causes of doubt in Christian belief, with 83% saying this was due to “past experiences with a religious institution,” 80% attributing it to “the hypocrisy of religious people,” and 62% indicating it is due to human suffering.

The full report is available here. The margin of error is plus or minus two percentage points.