Thanks again, people.
I have a question.
Do mormons really believe in magic underpants?
Yes, in the same way that Jews believe in magic fringed blankies.
Some Mormons like my wife think of the garments as a reminder of one's religion with no particular supernatural powers of their own. Others ascribe to them all sorts of literal magic powers, like a supernatural force field.
Even church leaders have waffled on which it officially is, though the force-field explanation is harder to find official church backing for, because of course it's falsifiable.
The link that Pixel42 posted points out the range of views, and clicking further from that link, to
http://www.mrm.org/underwear gives more information.
One thing that article misses is that there's another interpretation of "When properly worn it provides protection against temptation and evil," which is more literal than magical. This is how my wife explained it. "Properly worn" would mean don't take them off to have sex outside of marriage. I expect that most parents would urge their children not to strip down to their underwear in social situations if they didn't want things to lead to sex, so no magic force field necessary for that kind of protection from temptation. So the official claims of "providing protection" are not
necessarily supernatural, depending on how any individual Mormon interprets them, but also can be taken by superstitious Mormons as far as they want.
A further click goes to this blog article:
http://blog.mrm.org/2011/05/sacred-mormon-garments-work-like-a-charm/
Oddly, that article seems to hint that Mormons who claim the garments are just reminders of one's religion are somehow lying or hiding something:
"When Donny and Marie (and other Mormons) present Mormon undergarments as mere symbolism they effectively avoid the need to provide what would surely be an uncomfortable explanation of something that is not only 'sacred,' but that also works like a charm."
Since the author apparently hasn't lived with a Mormon and done her laundry and seen the whole interaction with the clothes for a couple decades, the author is misunderstanding that there really are different views within the church.
It's not that
all Mormons think the garments have supernatural powers of protection and some hide the belief better than others. It's that Mormons really do have different beliefs. Some are sincere when they say the garments are mere symbolism, while others are sincere when they claim the garments are supernatural charms.