Okay, first of all, I'm a Christian; in fact, currently studying to become a Lutheran minister. I am also an avid D&D gamer, having found no grounds whatsoever for linking D&D to anything immoral or spiritually unhealthy. I believe that religion, when properly used, is a positive influence that can uplift and inspire humanity; I also believe that gaming, when properly used, enriches the human experience socially and mentally. And I am appalled at the actions of this charity.
However, I ask people not to be too quick to blame the charity itself. As has been said before, it is entirely possible that they were under pressure not to accept our "tainted evil blood money". As surprising as this may be, there are still folks who don't know anything about D&D beyond what they heard from sensationalists in the 80s (notably, my parents were in this group until I started playing!) and I would not blame a charity for not wanting to scare off such people based on a misunderstanding. However, I feel it is their responsibility to set the record straight. Currently I can find no mention of this incident on their website; it seems they are trying to pretend it didn't happen. I would urge them (and urge you to urge them) to explain themselves, in public. If they are honest and loving people (as I would hope they are!) this would be an opportunity to both apologize to gamers worldwide and maybe cast a low-level "Dispel Ignorance" on some well-meaning but misguided people.
Or perhaps they will simply post the same half-hearted, half-baked mea culpa form letter that the people here have been receiving. In which case, they receive not one thin dime from myself, or anyone else I know, for a very long time.