 However, that provision, dating back to 1868, is unenforceable and invalid because the United States Constitution prevents religious tests for public office.A 2015 Gallup survey found that 40% of Americans would not vote an atheist for president, and in polls prior to 2015, that number had reached about 50%.A 2014 study by the University of Minnesota found that 42% of respondents characterized atheists as a group that did "not at all agree with my vision of American society", and that 44% would not want their child to marry an atheist.