By Sara Grossman, CNN

(CNN) -- If you’re applying for a new job, it may be best to leave religion off your resume, according to a new study.

Job applicants who mentioned any form of faith affiliation on their resumes were 26% less likely to be contacted by employers than candidates who didn't, according to the study conducted by sociologists at the University of Connecticut.

Muslim, pagan and atheist job applicants were the least likely to get callbacks from potential employers.

“People have a fear of the unknown,” said Michael Wallace, a co-author of the study and a sociology professor at the University of Connecticut. The study “implies that when people don't know much about a religion, they have an instinctive fear of that group.”

Jewish applicants received the least discrimination of all religious applicants, with evangelicals nor far behind.

The researchers sent out 3,200 nearly identical resumes to 800 employers around two major cities in the South, changing only a reference to participation in a religious student group while in college, including affiliations to evangelical Christianity, Islam and Judaism. The study does not name the cities.

A control group of resumes featured no reference to any religion.

The researchers also included a fake religion, called “Wallonism,” to measure the degree to which people discriminate against a completely unfamiliar faith. The fact that employers discriminated against “Wallonians” confirmed this suspicion, Wallace said.

The nonreligious resumes received responses about 18% of the time. By contrast, less than 11% of Muslims heard back from employers, followed by 12% of atheists and about 13% of “Wallonians,” Catholics and pagans.

Evangelicals heard back just under 16% of the time, while Jews heard back about 16.5% of the time.

The study showed that employers in the South -- the country’s most religious region by many measures -- prefer applicants who are not public about their religious affiliations, according to the University of Connecticut researchers.

“While religion is central to Southern life and Southerners more openly display their religious beliefs than citizens in other parts of the country, they also embrace the secular notion that there is a proper time and place for religious expression,” the authors wrote.

“Thus, even in the deep South, most employers draw the line against overt expressions of religious belief in the workplace.”

Religion in the United States has become “compartmentalized,” Wallace said. It is perfectly acceptable to be religious, he said, but Americans prefer that expression be secluded to certain domains.

“Social institutions are where you have a great diversity of people,” Wallace said. The worry that religious people might try to push their beliefs on other people is the biggest reservation of employers, he added.

The negative consequences of open religiosity did not seem to apply to Jews, however.

Although Jewish applicants received slightly less feedback from employers than applicants who made no mention of religion, this discrepancy was not enough to be statistically significant, Wallace said.

The researchers cited a number of theories as to why this phenomenon might be, especially since Jews make up a tiny portion of the Southern population.

For one, Jews have integrated well in the region and are not as residentially or occupationally segregated as they are in other parts of the country, Wallace said.

Also, evangelicals -- who make up the largest religious group in the South -- have a close affinity to Jews, even more so than to Catholics, and may feel more connected to members of this religious group, according to Wallace.

“Jews, and especially the Jewish state of Israel, feature prominently in evangelical Christian theology; in fact evangelicals express stronger support for Israel than any other ethnic or religious group except Jews themselves,” the researchers wrote.

Rachel Kranson, an assistant professor of religion at the University of Pittsburgh, said that part of this phenomenon might be a race and class issue, rather than a religious one, as the vast majority of Jews are white and middle class.

“People's religious identities do not exist in a vacuum, and intersect with categories of race and class,” she wrote in an e-mail. “Employers' preference for Jews may also indicate a preference for white workers from well-off backgrounds.”

The conclusions of this research largely mirrored those of a study performed last year in New England by the same team of University of Connecticut sociologists.