There are two main human urges: sexual urge and aggressive urge.
Our brain wants these two urges satisfied at all times, regardless of the consequences, which is the cause of many of the "unwanted thoughts" that haunt OCD-sufferers. All people get these "unwanted thoughts" because all people have sexaul and aggressive urges. One of the absolute safest things you can do to satisfy this urge is to visit a porn site. If you have a girlfriend or wife, satisfy this urge with them, so long as it doesn't become a problem of some kind. I have very strong OCD and I see a therapist for it, and sexual obsessions haunt me daily to the extreme.
That being said, I visit porn sites daily, on some days I spend hours on porn sites, even if it never leads to masturbation or anything. Looking at porn is pleasurable and there is nothing wrong with it, and so long as your visits to porn sites do not affect the rest of your life negatively, then visit them all you want. One of the worst things you can do with sexual urges is to repress them. This can sometimes lead to severe sexual problems.
One of the major problems with modern religion is that it puts the ideas of fundamental rules in our head, like masturbation is bad, and porn is bad. The facts are, we are animals and if we didn't have laws and such, we'd be having sex with our family, friends, aunts, uncles, etc. The laws, taboos, and rules come from very arbitrary and invented causes, not fundamental morals. We repress the urges to have sex with close ones because they are taboo, and also because sexual attraction is often numbed with brothers, sisters, mothers, fathers, but that doesn't mean it's non-existant.
Remember this: it is impossible to do something morally wrong by yourself, unless it involves cutting or hurting yourself. Spend an hour a day on porn sites, or spend 10 hours a day on porn sites. Neither is morally wrong unless they affect the rest of your life negatively.
