See also: Jacob 2:27-30
I wish to state categorically that this Church has nothing whatever to do with those practicing polygamy. They are not members of this Church. Most of them have never been members. They are in violation of the civil law. They know they are in violation of the law. They are subject to its penalties. The Church, of course, has no jurisdiction whatever in this matter.
If any of our members are found to be practicing plural marriage, they are excommunicated, the most serious penalty the Church can impose. Not only are those so involved in direct violation of the civil law, they are in violation of the law of this Church. An article of our faith is binding upon us. It states, “We believe in being subject to kings, presidents, rulers, and magistrates, in obeying, honoring, and sustaining the law” (A of F 1:12). One cannot obey the law and disobey the law at the same time.
There is no such thing as a “Mormon Fundamentalist.” It is a contradiction to use the two words together.
More than a century ago God clearly revealed unto His prophet Wilford Woodruff that the practice of plural marriage should be discontinued, which means that it is now against the law of God. Even in countries where civil or religious law allows polygamy, the Church teaches that marriage must be monogamous and does not accept into its membership those practicing plural marriage. — President Gordon B. Hinckley, Ensign, November 1998, p. 71-72