Why are there so many different Christian denominations that claim....?

Why are there so many Christian denominations that claim that they don't interpret the Bible and that they just follow it literally, and yet their only similarities are their belief that ity is a sin, that evolution didn't happen, and that abortion is murder? It would seem to me that since everyone claims that they don't interpret the Bible and follow it literally that there would only be one Evangelical or Fundamentalist denomination. Also, why does every single denomination, including those who call themselves "non-denominational", claim to be the right one?