Well, in a purely deontologic moral system, the beliefs are like "Don't torture people, torturing people is bad".

Is there any such a "pure" system? Deontological metaethics has to put forward a justifications because it is philosophy. I don't see how you can arrvie at yoru conclusion without performing the double whammy of both ignoring what people who call themselves deontologists say, AND dubbing the attitudes of some unreflective people who don't call themseles deontologists "deontology".