The population is about 51 % Roman Catholic , and 31 % of people are agnostics or atheists . 4 % are Muslim , 3 % say they are Protestant and 1 % say they are Jewish . The poll showed 51 % identified as being Catholics , 31 % identified as being agnostics or atheists ( another poll sets the proportion of atheists equal to 27 % ) , 10 % identified as being from other religions or being without opinion , 4 % identified as Muslim , 3 % identified as Protestant , 1 % identified as Buddhist , 1 % identified as Jewish .