Accepting gay marriage would not destroy the church's spiritual fabric, instead it would allow the church to develop a new spirituality. It might also lift a kind of heaviness that permeates church culture. Marriage for the LDS Church was once between a man and many women (and the LDS church continues to believe that this is the case in the afterlife). When the church abandoned the practice of polygamy, it didn't lose its way spiritually, it found a new spiritual life, one that reflected the material, social and ethical advances of the time. Now many religions are struggling with a radically changed social sphere that is the result of material, social, political and spiritual change. I don't think the world is going to become less complex, and I suspect many religions will slowly over time adapted to this new terrain.
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