Until the latter 20th Century, practically every human belonged to one superstitious cult or another, as Sam Harris points out in his book. Today, however, various estimates of the numbers of religious nonbelievers fall into a ballpark of 800 million to 1 billion. These numbers are comparable to, if not greater than, the entire human population alive about 200 years ago, so by the demographic standards of the early 19th Century CE, the world is full of "infidels."
The implosion of religious belief even in countries where people are free to study and practice any religion they want (e.g., much of the European Union) should cast considerable doubt on recent claims that we have "god genes" which predispose us towards religiosity. Ironically the levels of religious belief in Israel, a country which figures so prominently in American fundamentalist imaginations, are more in line with secular-humanist Europe's than Jesus-loving America's.