To the original point of the thread, I think a sensitive balance is involved in transitioning our children from a sheltered life to exposure to the world at large, be it for moral reasons or to avoid some of the ugliness of violence in the world.
I think media that present points of view that oppose our own provide a good opportunity to start conversations with our children about the basis for our views. However, parents are the best gauge of their children's maturity, and I think it is entirely reasonable for parents to limit their children's exposure to challenging or morally complex topics until they determine their children are ready to hear reasoned arguments. There's a delicate hand-off between building a cognitive and moral foundation for your child, and helping them become independent thinking, self-sufficient adults.
As a Catholic, I'm going to have to become proficient at planting seeds of discussion as DS grows older, as my beliefs diverge from secular views on a handful of issues of conscience. I will almost certainly censor his access to some topics, moral and otherwise, until he reaches the age of reason. Pornography is one topic that comes to mind.
