| Purple Ork |
To try and steer things back to the point of the post.
Zon-Kuthon on the surface seems like a CE or NE entity, he wears spikes and chains, tortures people for the fun of it, and is just down right horrible capital E for Evil deity. The guy is everything a death metal band wishes they could be and more. On the surface, but, when you you look deeper you see a restraint to his madness, and that is the key to Lawful in his alignment. He, and by extension his faith, restrain themselves. They torture, and mutilate, both others and themselves for pleasure and to find some twisted perfection, but only when it is "proper" to do so. They save their horrors for those that have broken the law as punishment, those they own legally as property, and those that volunteer for the experience. In addition we see that Zon-Kuthon himself keeps his word and bargains, and his faith are shown to have a solid hierarchy that all loyal fallowers of the faith keep to.
This is just my 2 cents though.