You are wrong. Mormons use the King James version of the bible, and use the book of mormon IN ADDITION to the bible. They believe that the book of mormon is a history of the americas, in much the way the bible is a history of the middle east. Does studying american history mean you dont believe in europian history? I dont think so. The bible is FULL of plural marriage, so I dont see how you can condemn the early mormons for their practice of it without condemning its practice in the bible.I do. They do not go by the bible nor does the bible mention mormonism it it. They have created a so called "extension" or another book of the bible calling it the book of mormon. Mormonism was created by a horny man wanting to screw more than one woman so he made it up saying GOD told him to do so. Women fell for it.
If you want to hate Mormons, thats fine. But at least learn enough about them to know that the reasons you use for hating them actually exist.