Will Herberg wrote his now famous book Protestant, Catholic, Jew: An Essay in American Religious Sociology. According to Martin Marty, Herberg's book "spoke precisely to the mid-century condition and speaks in still applicable ways to the American condition and, at its best, the human condition. Herberg argued that "America is a three religion country"--Catholic, Protestant, and Jew.
Today, according to this study from the Public Religion Research Institute, we live in a country dominated by three types of religious people: Catholics, Evangelicals, and the unaffiliated.
It's time for a new book. Who is going to write it?