Aside from this historical theme, has been the observation that in the US, the States with the highest illiteracy rate rank also the highest in those that practice Christianity. This point is hard to get around. And the resilience of piety nests in this observation. And in my opinion, piety finds it's strength in numbers as well as emotional behavior driven by fear. Personal accountability is mostly absent in the Christian life, "it is God's Will", or that they weren't even accountable for their owns sins and, that by their own admission, a projected Savior had to do that for them as well.
If Christianity were on trial in a court room, it's case would be very weak. The Bible as their keystone is a text of astrology and mysticism bathed in ambiguity and easily interpreted to fit the their means at any given moment, for any common defense. The historical Jesus is awash in this system and bound to drowned by sheer weight of facts.