Sex and Violence

I recently attended a showing of Angels and Demons with my kids. The movie, which was rated PG-13 was full of violence. The plot involves a series of murders and attempted murders including burning a man alive, poisoning, drowning, stabbing, shooting, and a car bomb. I wonder why this level of violence is considered OK by the film ratings board when sexually oriented nudity or expletives if "as must even one of those words used in a sexual context" requires an R rating.

I am willing to bet that the parents of everyone reading this have had sex and have used a dirty word. I'm also willing to bet that almost none of them has shot, set fire to, drowned, poisoned, or bombed another person. We're not killers and we have sex, so why is violence in the movies OK for 13 year olds, but sex forbidden? I'd far rather have my kids think that sex occurs frequently and murder doesn't happen often than have them watch movies that imply it's the other way around.