Mormon writer and professor David Mason has finally spilled the beans on Mormonism, admitting that Mormonism is not Christianity -- indeed, he says it is no more a form of Christianity than Christianity is a type of Judaism. That is, just like Christianity came from Judaism, Mormonism came from Christianity (and Judaism). However, Christianity is not Judaism, despite its origins, nor is Mormonism a type of Christianity. Mason notes that this argument is also advanced by Richard B. Land of the Southern Baptist Convention who argues that Mormonism is a "fourth" Abrahamic religion, separate from Judaism, Christianity, and Islam.
Of course, Mason notes that most Mormons vehemently insist that they are Christians. They often do so because they believe that Jesus is divine in some sense. However, Mason points out that Mormons do not accept the Trinity, which is central to most forms of Christianity, except Unitarianism, and therefore reject the Nicene Creed's formula that Jesus is also to be identified with "the Father" and "the Holy Spirit". Therefore, while Mormons "believe in Jesus", the Jesus that they believe in is radically different than the one that almost all Christians believe in. By the way, many Christians do not consider Unitarians to be legitimate Christians either.
Mason points out that, once Christians finally came out and admitted that they were not actually authentic Jews, it allowed them to establish their own identity, and they ended up being quite successful there. Likewise, he feels that Mormons should just admit that the religion they practice is not authentic Christianity of the form that has been practiced for almost 2000 years and move on. I am not sure that they will be lucky enough to share in the accidents of history that catapulted Christianity so far up the social ladder.
I suspect that Mormonism, as prudish as it presently is, will either be forced to undergo radical change, or it will radically decline, just as we are seeing in many ultra-traditionalist sects of Judaism, Islam, and Christianity.