|I'm sorry that I missed this topic, and I hope you don't mind me responding a bit late. I might have some insight here as I was raised Mormon, and was thoroughly converted to the faith for 23-24 years. I also served two years on a mission to convert people to the church. I baptized somewhere around 30 people into Mormonism, a majority of them being adults.
Converting to Mormonism in adulthood now seems absolutely absurd to me. Then again, I, like most of you, have a very clear and reliable method for arriving at what we accept as true. We are very concerned with reason and evidence.
We have to realize - with some degree of dismay - that most people don't have a clear method for arriving at moral truths. An argument from the position of reason might sound just as convincing as the argument that there are millions of people who believe these things - why don't you?
In the case of Mormonism, the method is a very cheap trick. First, we were taught to "build relationships of trust." Since that sounds so manipulative, the Mormon leaders re-phrased the method, but you are supposed to get people to trust you before teaching.
Next, "Elders" (the 19-21 year olds) and "member missionaries" will often say things like "I know the church is true with every fiber of my being." They will repeat these "I know" statements so often with such conviction that you begin to believe that these people actually know something. This can actually have quite an effect coming from someone you trust and respect. I would bet that Beck's Mormon friend in radio did this more than once.
Finally, there is a strong appeal to your emotions. You are told to read the Book of Mormon and pray about its truth. "I know that if you do this," I would say very sincerely, with emotion, "God will tell you in your heart and mind that it is true." It's basically the standard religious appeal to use feelings (vs. rational thought) to find the truth.
What really happens: A missionary tells the investigator that he "knows" the truth. He might have a tear in his eye, and you can tell he really believes it. The investigator believes him, or at least feels a sense of empathy at this uncommon outpouring of emotion.(thought) The investigator then feels emotional (feeling)
What you are taught: The feelings you are feeling are from God (feeling), and he is confirming to you through your feelings that what the missionaries are telling you is true. (thought)
The real trick is just to convince people that they are feeling things about what they should think and believe. Once someone is blinded to the fact that the reverse is true - that they are just having feelings about what they think - you just have to make things very emotional. People like me who are very empathetic can be pulled into this very easily if they're not careful. When I see someone showing intense emotion I feel a very deep sense of empathy, and may get emotional myself.
Go to a Mormon church on the first week of the month if you want to see this method in action.You are likely to see a lot of people on the stand crying about how they "know" something. There will be several people in the audience weeping as they do this. (But this next month might be a little bit different, as they will be talking about "this great country" quite a bit.)
The thing is that Mormons are taught to begin saying they "know" very early into their conversion or childhood The member missionary thinks he/she is "teaching by the Spirit" when he/she gets very emotional. The point is that it's an almost purely emotional appeal, and people who believe in "going from the gut" like Beck does are easy prey. The more someone appeals to logic to answer questions of fact, the less likely the conversion.