Mormon fundamentalism is a type of Mormonism, which is a religious belief. Mormon fundamentalism is an extreme form of Mormonism that was created in the late 1800s. The main idea behind Mormon fundamentalism is that it follows religious ideas and practices that are very traditional and are not accepted by the main Mormon church. This means that they may not believe in all of the same things as other Mormon churches. For example, they may not believe in women being able to serve as church leaders. Mormon fundamentalists also practice polygamy, which is when a man has more than one wife, which is not accepted by the main Mormon church.