[/nostalgia]
Brings back memories. Played my first Fighter when I was 6 and graduated to my first Paladin not long after that waaaay back in 1E AD&D. DMed for the first time not long after for my cousins (ages 6 or 7 to 12) and got them interested in the game... good times.
Admittedly, my first Fighter was little more than a bodyguard to my Mom's Cleric. Considering that the people we played with were 10-20 years older or slightly more, there wasn't too much I could contribute to that game. But still, I became an avid reader of the books, including the Monster Manuals and Deities and Demigods, which introduced me to mythology, philosophy and books all at the same time.
[/nostalgia]
From experience on both sides of the equasion, I have to disagree on the religious front. If your kids can handle a cartoon (Dragonball Z, Aladdin, Hercules, etc.) and real life, they can handle the fact that not everyone at every point in time is or was <insert your religion here>. They can also handle the fact that not everyone is nice.
Not saying that you should jump into mature elements feet first, of course (heck no), but gods, goddesses, angels, demons and devils are good fodder for 'morality plays' in DnD, even for kids. I know I loved them, and the kids I've introduced to the game handle it fine. Particularly squashing Demons (and they love that part).
Still, I don't think the educational value of RPGs and be overestimated. What other hobby exercises imagination, creativity, problem solving, english and basic math while introducing elements of philosophy, history and practical knowledge?