To an atheist such as myslef, the entire concept of sectarianism is baffling. Well, I suspect the concept isn't particularly baffling. What surprises, is that none of the things on your handy dandy comparison chart (which is superficially accurate) are being argued about. In other words, the conflict is not about whether we should accept the Bible and tradition, or just jettison the latter, or exactly which books are in the Bible, or the precise relationship between nature and grace and so on In fact, I suspect none of these debates (alas) are of any interest at all to the two sides. Atheist as I have said numerous times until you engage the deeper historical and cultural issues, you have no hope of understanding the world you live in, and why it has become increasingly violent.