With special emphasis upon his interpretation of the sociological significance of religion in the U.S.A. and the ways in which that interpretation relates to the views of Weber, on the one hand and Troeltsch, on the other, this paper highlights the main general themes relating to religion in Parsons' evolutionary action theory. In a primarily exegetic vein, and with special attention to Parsons' writing from the mid-1960s up to his death, the discussion involves a reconstruction of Parsons' conception of the evolutionary significance and the evolution of Christianity, in particular, and religion, in general, in the making of the modern global-human system.