In that sense, Bellah`s work is truly interdisciplinary. He is running significant risks here, because he is difficult to classify. This is not sociology, history, or anthropology, as normally practiced; nor is it, strictly speaking, evolutionary or cognitive science. It is all of these, and none of these.
Sounds like a description of the study of religion to me. That being said, what makes Bellah's work special in this case is that all these things are integrated into one package.