Don't get me wrong, I'm not a fan of Mormonism. I am a fan of Mormons though, having never met one I didn't like. Same goes for Wiccans, they all seem pretty nice... though outside of fundamentalism it's hard to find unlikable people. In any event, Lawrence O'Donnell goes on an interesting rant about Mormonism, he has, for the most part, facts on his side. He's right Mormonism is a racist pro-slavery religion founded by a criminal in the most absurd manner. However, there are a couple problems with attacking the religion. First, you aren't establishing they are wrong. Second, Tu Quoque.
The fact that Mormonism is inherently racist, or was until push came to shove and the Church leaders suddenly got a new vision, is not a logical mark against it. Did Mr. O'Donnell consider the possibility that blacks actually did have their skin color changed to reflect their evil nature prior to the creation of Earth, just as the Lamanites had their skin color adjusted to match their wickedness? It is an ad hominem as stated: that has nothing to do with how truth or falseness of a religion. However, the Book of Mormon contends that it was written in 600 BC (it says that, this book is being written 600 years before Christ, it calls it a prediction) and at that time, there wasn't any racism. In fact, racism wasn't invented until the 17th century. Moreover, it was very common place in the time and place that Joseph Smith lived. Racism can and does contribute to an argument of anachronism. If a religion was formed in 600BC Israel it should not be racist. If a religion was formed in the 1800s America it should be.
Secondly, as Pat Robertson notes (I have before been impressed with his commentary, he's a blowhard when it comes to religion, but with commentary he's sometimes on the mark) that Christianity brought slavery to America. Slavery is permitted in the Bible. It specifically says in Leviticus 25:44-46:
Both thy bondmen, and thy bondmaids, which thou shalt have, shall be of the heathen that are round about you; of them shall ye buy bondmen and bondmaids. Moreover of the children of the strangers that do sojourn among you, of them shall ye buy, and of their families that are with you, which they begat in your land: and they shall be your possession. And ye shall take them as an inheritance for your children after you, to inherit them for a possession; they shall be your bondmen for ever.
And the holiest of holies the Ten Commandments drops the nice little line at number ten (Exodus 20:17):
Thou shalt not covet thy neighbour's house, thou shalt not covet thy neighbour's wife, nor his manservant, nor his maidservant, nor his ox, nor his ass, nor any thing that is thy neighbour's.
Listing off slaves as another bit of property.
The dumbest line was "I am not comfortable dissing an entire religion. We are a pluralistic nation." -- Who cares what you are comfortable with! I'm comfortable with dissing all religions. Pluralism is just a silly way to say that there are many many one and only one Gods.
A rather devastating non-argument against Mormonism gets matched up with a crowd which notes that Christianity sucks too (Pat Robertson) and a we should just declare and embargo on discussing any religions in specific language.