I am against p 0 r n too, because it objectifies and dehumanizes human beings into a body without emotions. It is vile and makes people think it is ok to have sex with strangers, with your neighbor, with your mother, with a group of people no matter how much disease can be spread.
Nonetheless, as an atheist, of course I know there is no such thing as the devil, a figure created by men centuries ago when they didn't have any knowledge of Science and to instill fear in people so they would behave. The devil goes along with the Loch Ness Monster, the Freddy Kruger and other fantasies.
So let's keep religion out of this. Reigion does not guarantee morals. The bible belt is where more divorces and rapes and fathers abusing their daughters mostly take place according to statistics. Just see the latest rape news on the Amish.