There is no such thing as a polygamous Mormon. This sect separated from The Church of Jesus Christ of Latter-day Saints (often referred to simply as Mormons by lazy journalists) when said Church discontinued polygamy a CENTURY ago. This group calls themselves Fundamentalist Latter-day Saints, a crucial distinction, especially for me. Loose, casual descriptions and fictional TV like Big Love have made it so that my sons (who I am raising as members of the Church of Jesus Christ of Latter-day Saints) apparently will never be able to be president. At least get it right so that my sacrifices for my faith are respected. See lds.org for more information. Unlike most (maybe all?) other religions mentioned, we Mormons have a central authority which all true Mormons defer to and thus have the ability to truly excommunicate someone from our church. You are not Mormon simply because you believe in the Book of Mormon or any other single tenet of our faith, or even because you SAY you are. Single congregations don't vote on what they decide they will believe: it all comes from our headquarters in Salt Lake. See lds.org for more information.