"Autism is a different way of seeing the world. Sometimes it makes living in the world difficult, because it doesn't make sense. Sometimes the people with autism can cope with the world, sometimes they can't. Sometimes it's on a day-to-day basis."

I get a bit annoyed with my 13 year olds who are rude about autistic people and explain it like this. That makes more sense to them than "they are stupid" or however they have been explaining it to themselves and each other (along the "stupid" lines usually).