But this brings me to the more fundamental issue. Theology and texts have far less power over shaping a religion’s lived experience than intellectuals would like to credit. This is a difficult issue to approach, because even believers who are vague on peculiarities of the details of theology (i.e., nearly all of them!) nevertheless espouse that theology as true. Very few Christians that I have spoken to actually understand the substance of the elements of the Athanasian Creed, though they accept it on faith. Similarly, very few Sunni Muslims could explain with any level of coherency why al-Ghazali‘s refutation of the Hellenistic tendency within early Islam shaped their own theology (if they are Sunni it by definition does!). Conversely, very few Shia could explain why their own tradition retains within its intellectual toolkit the esoteric Hellenistic philosophy which the Sunni have rejected. That’s because almost no believers actually make recourse to their own religion’s intellectual toolkit.
This is the hard part for many intellectuals, religious or irreligious, to understand. For intellectuals ideas have consequences, and they shape their lives. Their religious world view is naturally inflected by this. And most importantly they confuse their own comprehension of religious life, the profession of creeds rationally understand and mystical reflection viscerally experienced, with modal religiosity. This has important consequences, because intellectuals write, and writing is permanent. It echoes down through the ages. Therefore our understanding of the broad scope of religious history is naturally shaped by how intellectuals view religion. In a superficial sense the history of religion is the history of theology, because theology is so amenable to preservation.
Like the old joke about the drunk, we look for the keys to understanding religion in theology because the light's better there. I think this is clearly true, and it also underlies why I think it's so ridiculous to hear atheists talk about forming a world without religion, as if it would simply be a matter of convincing people to reject certain logical propositions through argument, as opposed to a complete remaking of human psychology and culture along rational lines, which, of course, worked so well for the Jacobins and their offspring.