I define the difference between a religion and a cult as how much control it tries to exert over its membership.
In Mormonism, you have requirements to wear special undergarments, requirements to send your kids off on missionary work, requirements to tithe, requirements to spout off your testimony on demand. If that isn't a cult, I'm not sure what is.
But I use a simpler yardstick. If you leave Mormonism, your relatives and friends are required to shun you. When I left Catholicism 30 years ago, none of my friends or relatives shunned me or even questioned my decision.
I am a member of the Church of Jesus Christ Of Latter Day Saints.
As a member of the church you are not "required" to do anything. In fact, a closer look at the doctrine of the church would show you that free agency is a cornerstone to the teachings of the church.
Over half of the church membership (on the roles) is "inactive" (don't do any of the things you describe and don't attend church).
I personally do the things I do within the church, such as tithe, because I have a strong belief in it's purpose. If I quit tithing, I would not lose my membership.
The shunning you describe is more a cultural problem. In fact, church leaders have often decried this as wrong. They also get after the Utah mormons for being such cliques.
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Having said that , Romney's membership in the church is going to be an issue if he is nominated and the church is going to catch it during the campaign.
Recall that Romney got crosswise with Mike Huckabee over MH's comments about his religion during the 2008 primary.
And when Romney ran against Ted Kennedy for the Mass Senate, the church's position on blacks and the priesthood became a key attack point of Kennedy's campaign (Romney facing a black president is going to be a very polarizing situation).
And then there is the church's position on gay marriage. Regardless of what Romney may or not may say, he will be tied to the church's pretty strong stand on marriage.
I don't look forward to all the myths that will fly, but if Romney is the best man for the job, then I guess it is just what will have to be dealt with.