"My 6-year-old is very interested in reading non-fiction stuff."
I always found when raising my two boys that a good historically accurate movie was always a good place to start to peak their interest. I would recommend one like Mel Brooks', "History of the World, Part I" or his and Carl Reiner's "Interview with the 2,000 year Old Man" for starters.
"Who is it, Lord?"
"Judas!!"
"What?!?!"
"Would you like the mulled wine? It's stupendous!"
Just like in the Bible. ;-)
Thanks for the ping, guys. I've been following Cornuke's work for a few years now, and I'm looking forward to see what other information is forthcoming.