Whom would you trust more, an atheist or a rapist? In one international study, respondents preferred the rapist. If that's representative, atheists are among society's most distrusted people; even violent criminals get ranked higher.

Yet self-described atheists are anything but uniform. Even the dictionary definition of a lack of belief in a deity does not necessarily apply, according to objective research. Perhaps this impossibility of accurate categorization in part explains the lack of trust.

Psychologists at the University of British Columbia and University of Oregon questioned nearly 800 American and Canadian adults in 2011. They were asked to decide among likely culprits of two fictional scenarios: a driver who damaged a parked car and left the scene, and someone who found a wallet and took the money. Asked if this fictional culprit was more likely to be an atheist, a rapist, or neither, most respondents picked the atheist.

The researchers, who sought to understand the psychological needs religion fills, concluded that anti-atheist prejudice stems from moral distrust, not dislike, of nonbelievers. Among their conclusions is that religion helps provide a sense of trust in others. Believers assume atheists are without morals, said the researchers, so they are feared as a group.

"If you realize there are all these atheists you've been interacting with all your life and they haven't raped your children, that is going to do a lot to dispel these stereotypes," one researcher told The Washington Post.

What is an "atheist" is as difficult to pin down as what is "religious." According to Pew Research surveys conducted between 2007 and 2012, American atheists (whose numbers along with agnostics and "don't knows" are increasing, while those who identify as religiously affiliated are steadily decreasing) are not one uniform group. In fact, 14 percent who self-identify as atheists say they believe in god, or some form of universal spirit. More than 80 percent say they feel a deep connection to nature, about 30 percent describe themselves as spiritual, and others describe a strict moral code they live by. More than 40 percent say they often think about the meaning of life. Pew Research respondents also included those who affiliated with a particular faith or church, yet said they don't believe in god.

What is "atheist" and "religious" is apparently more a matter of personal interpretation than agreed vocabulary.

Several studies have shown high degrees of volunteerism in those affiliated with churches. Yet atheists are apparently generous too, if motivated differently. One study published in the May 2012 edition of Social Psychological and Personality Science Journal concluded that less religious people were more apt to give away money than are those who described themselves as "highly" religious. This study focused on feelings of compassion and combined data from a 2004 national survey of 1,300 American adults, with later experiments involving more than 300 young adults.

Responding to videos and hypothetical scenarios, less religious participants were reported by researchers to be more likely than those who are more religious to give their "lab dollars" to co-participants, strangers, and homeless people. The study found "that although compassion is associated with pro-sociality among both less religious and more religious individuals, this relationship is particularly robust for less religious individuals."

Those researchers concluded that for less religious people, the strength of their empathetic or emotional connection to another individual was the critical point; whereas for the more religious study subjects, generosity was more connected to factors such as doctrine and a communal identity. Both have their roles in society.

Sholeh Patrick is a columnist for the Hagadone News Network. Contact her at Sholeh@cdapress.com.