Mark Chaves, of Duke sociology, has written this very interesting paper about what he calls religious congruence (or, more appropriately, religious incongruence).
He uses "'religious congruence' in three related senses: (1) individuals' religious ideas constitute a tight, logically connected, integrated network of internally consistent beliefs and values; (2) religious and other practices and actions follow directly from those beliefs and values; and (3) the religious beliefs and values that individuals express in certain, mainly religious, contexts are consistently held and chronically accessible across contexts, situations, and life domains. In short, it can mean that religious ideas hang together, that religious beliefs and actions hang together, or that religious beliefs and values indicate stable and chronically accessible dispositions in people."
He then makes the case that "people's religious ideas and practices generally are fragmented, compartmentalized, loosely connected, unexamined, and context dependent. This is not a controversial claim; it's established knowledge. But this established knowledge does not inform our research and thinking as centrally and deeply as it should."
I like this article because it moves us away from holding up an ideal of religion as some tight, consistent scientific proposition, and it allows for a messier, richer understanding of it. In that sense, religion is much more like everything else in life than it is a scientific equation.