A survey of U.S. atheists and agnostics has found that the typical freethinker is male, 58 years old and has at least one college degree.
The Freedom From Religion Foundation surveyed its nearly 4,000 members and more than 1,300 responded.
The survey found that 73 percent of respondents had one or more college degrees compared to less than 25 percent of the general population.
Nine percent of respondents reported having earned a doctorate, a total that is 10 times the 0.9 percent figure for the general population.
"The educational pursuits of our members bear witness to the fact that most people who reject religion do so mainly on intellectual grounds," said Anne Nicol Gaylor, president of the Madison, Wis.-based foundation, in a statement.
"The most common catalysts cited for rejecting religions are reading, education, intellect, science and other thought processes."
The survey found that 17 percent of those responding were raised in "freethought homes" while almost three-quarters of respondents came from religious backgrounds.
Twenty-nine percent had rejected Roman Catholicism, while 19 percent left behind Methodist teachings, 14.5 percent rejected the Baptist faith, 12 percent gave up Lutheranism, and 9 percent rejected Presbyterianism.
The survey also revealed that many freethinkers feel alone in communities dominated by believers.
One-third of respondents concurred with statements such as "I often feel like the only `infidel' in my area" and "I am wary of letting others know I reject religion."
But more than half of those responding agreed with the statement "I speak out freely about my lack of religion."
The survey also revealed a high percentage of senior members of the organization. Only 3.5 percent of those responding to the survey were in their 20s, compared to 22 percent in their 70s.
"Freethought is very strongly correlated with the wisdom of age," Gaylor said.
Nearly half of the foundation's members returning surveys are retired and 39 percent volunteer regularly.
Foundation members also are twice as likely to be male as female. Seventy-nine percent of respondents described themselves as atheists; 13 percent said they were agnostics.