I just don't see why Proposition 8 is so threatening to Mormons

The LDS First Presidency announced its support for Proposition 8 in a letter read in every Mormon congregation. Since then, California LDS leaders have prompted members to sign up volunteers, raise money, pass out brochures produced by outsiders and distribute lawn signs and bumper stickers. Bishops have devoted whole Sunday school classes and the weekly Relief Society and priesthood meetings to outlining arguments against same-sex marriage. Some have pointedly asked members for hefty financial donations, based on tithing. Others have even asked members to stand or raise their hands to publicly indicate their support.

Gary Lawrence, writing in the online Meridian Magazine, compared opponents of Proposition 8 to those who sided with Lucifer against Jesus in the pre-mortal existence. Others have questioned such members' faith and religious commitment, accusing them of undermining the prophet.

Literature written by Proposition 8 proponents is freely distributed in Mormon wards, giving the impression the church approves it, but much of it is "misinformation," said Morris Thurston, an LDS attorney in Orange County.
Thurston has circulated a point-by-point refutation to an anonymously authored document that has been widely disseminated by Mormons, "Six Consequences . . . If Proposition 8 Fails." Thurston argues that most of its arguments are either untrue or misleading.
He welcomes critiques of his analysis, but some have been hostile and many question his motives.
"I feel like I am entitled to my opinions, especially when they involve legal matters," Thurston said, "and I don't think I should be compared to Satan's minions."

From someone who was a Mormon:

My point is this: the Mormon Church is pulling out the stops. These kinds of wedge issues help them retain members by engaging them in "causes" that make people feel special and on God's side. There is no discussion in church or outside about fairness, the Golden Rule, and Unforeseen Legal Ramifications. Being part of a crusade is exciting... and never mind who gets hurt!

Update 10/27: Steve of SteveAudio has a wonderful post on the people who are against Proposition 8.

Update 10/30: Emptywheel of Firedoglake tells the story of her experience with Mormons and their hatred of gays.

John Aravosis of Americablog notes: Legal Adviser to Prop 8 Campaign Compares Gays Who Want to Get Married to Nazi Germany.

Update 11/3: Tengrain at Mock, Paper, Scissors posts a video.