Well it kinda boils down to which branch of Christianity you follow. Catholics, for example, shun masturbation altogether (bunch of prudes, no wonder so many people say they are "non-practicing" Catholics
). But if you look at masturbation from a non-denominational point-of-view, it is wholly NOT a sin. At no point in the Bible is masturbation even MENTIONED, most likely because it was such a normal, healthy part of life that they didn't see fit to put it in there. Catholics think it's wrong because it's "wasting your seed" which should only be used in sex with your wife, which is.... well it's stupid. We know full well that we can't "waste" that much if we produce millions of sperm everyday! AND IF WE DON'T MASTURBATE, we have a wetdream that "wastes" it all ANYWAY.
I support the ideals that the looking at women lustfully is a sin (I am a Christian, but sometimes the ways of the Catholic church bug me; since they base all their stuff on what "they" think is right instead of what God told them was right in the Bible....but anyway...
). I DO masturbate, and sometimes I really feel the urge to look at porn. Just.... try not to. My only suggestion (and I don't know if this is "cheating") is to watch hentai. When I can't help myself I watch it because "it's just cartoons right? They're not real women to lust after....right?". But of course I don't watch all that nasty tentacle crap. Like dude, what the hell are some of these animators thinking eh?