Not only has this been on my mind lately, it’s a good place to start. Christian churches and denominations distinguish themselves in all sorts of ways. These distinctions are often trivial or superficial. Within the broad range of those religious organizations which call themselves ‘Christian,’ I choose to categorize most fundamentally by source of authority.
Taking any characteristic of a religious group into consideration and asking why such a characteristic exists, one will eventually come to some sort of root assumption or assumptions. In reality these root assumptions are not chosen because they make sense. They are only ever chosen because they bring the owner of the assumption some sort of satisfaction. The satisfaction may be with the assumption itself, but it is more likely that the assumption allows for physical comfort, peace of mind, or a sense of significance.
In my experience there are only four general kinds of root assumptions utilized by nominally Christian organizations and individuals. They are assumptions about where truth is to be found: either within the teaching of a holy group/tradition, a holy document, subjective experience, or a holy person. These foundational starting places of belief are sometimes explicitly announced but are sometimes unknown even to those who embrace them.
I was planning to rant on about the pros and cons of each, but that will have to be left alone for now. What strikes me at the moment is the similarity between the four possibilities. They are all examples of what Rene Girard calls mimesis. He claims that all people have their identities rooted in the imitation of someone or something or some group.
I believe that, too a large degree, we can choose whom or what we will imitate. I choose (undubitably hypocritically) to imitate a person. The ‘Christian’ who roots belief and finds ultimate authority elsewhere is keeping his hypocrisy very close to the surface.