I have never encountered anyone who believed that D&D was evil, in a religious sense. I've run into one or two people who had heard the same sorts of stories about the game driving people to anti-social behaviour or suicide, but it was clear to me (at least in hindsight) that hearing stories about the crimes D&D "caused" (whether or not these crimes ever happened) was simply their only experience with the game - exactly the same as someone who's never been exposed to anime assuming that it's all stupid, overlong, melodramatic fight scenes like Dragonball Z.
As we all know, though, just because you show someone the truth about something it does not mean they are going to be interested in it or that they will approve of it. Anime is again a good example: I know it's not all childish garbage like Pokemon, but I've found other reasons why I have no time for it.
On the other hand, there are lots of things in this world I dislike - Nashville country music, Palladium games, fanfiction, home-improvement shows, romantic comedy films - and yet I don't crusade against them. I tolerate any interest my friends and family might have in such things while making it clear that I won't join them; I think gamers should strive to achieve that kind of acceptance from the people in their lives who question their hobby.
I don't know what your relationship with your parents is like, Corvidae, but if it's reasonably normal and healthy, you could talk to them about your younger brothers' interest in D&D from the standpoint of how playing the game since you were X years old hasn't ruined your life, hasn't torn you away from the religious and political values you presumably share with your parents, hasn't prevented you from growing up to be a happily-married adult leading a respectable life.
If you have any friends or relatives serving in the armed forces, you might write or call them and ask them if they know of any game groups where they're stationed. I doubt I could find the thread now - and perhaps it was lost in the forum crash in any case - but I remember a recent story about a soldier who was killed in Iraq who gamed. The photograph run in his hometown newspaper showed him gaming with some buddies from his unit. It's very likely that anyone you know in the service has heard about some kind of gaming group - there are even stories about how every nuclear submarine in service during the 1980s had a gaming group on board. I don't know if that's true or not.
If your parents like your wife and trust her judgement, you might ask her to help you talk to them about the game to ease their fears - if she knows of and accepts your hobby without sharing it, that might even be more helpful than enlisting the testimony of one of your gaming friends.
Finally, and you may well be planning to do this already, you could offer to help your younger brothers learn about the hobby by running games for them, so that they'll definitely be learning how to play from a responsible adult and not drifting on their own into a style of play that your parents would find objectionable.
I hope something I've written is of some use to you.
