I was actually thinking the similar thing: why aren't most religious people simply deists? I mean if they all claim that "all the religions are true in some way" and that "all gods are the same" then why adhere to Christianity or Islam or Hinduism... I mean if they claim how majority of Christians reject Bible's claims about the world like: flat Earth, six day creation, that the stars will fall from the sky onto Earth, six headed monsters, dragons etc. but adhere to the "God can be seen in the science of the Big Bang" then why not just let go of the rest of the primitive localized beliefs?
teachings of the Bible are so muddled and self-contradictory that it was possible for Christians to happily burn heretics alive for five long centuries. It was even possible for the most venerated patriarchs of the Church, like St. Augustine and St. Thomas Aquinas, to conclude that heretics should be tortured (Augustine) or killed outright (Aquinas). Martin Luther and John Calvin advocated the wholesale murder of heretics, apostates, Jews, and witches. - Sam Harris, "Letter To A Christian Nation"
