Maybe I am missing something, but watching erotic pictures (you say he mostly watches pictures of girls - that's not porn is it?) is not exactly an addiction, even if he is doing it in secrecy. He wouldn't be doing it in secrecy if you were accepting of him, would he?
I feel a strongly critical tone in your text. You also mention that you don't have sex with him that often (once every three weeks is very rare for a new couple). Could those two be related? Is there something that your husband craves in your relationship that he can only find in fantasies? Girls in picture can't criticize. And criticism is the best way to kill any sexual desire there is. Imagine if someone told you - wow you have a big butt... See what I mean? Same with - I can't believe you are watching porno pictures... I didn't quite see what your exact reaction was to that, and if you ever talked to him about it, but from "He just looks at pictures of naked women and THAT is what hurts and makes me mad!!** I can see that he certainly can at least feel your anger.
Would Jesus Christ criticize someone who is looking at sexy pictures, someone who is not doing it to hurt you? No. Lust does weaken a person, but one can lust even after his own wife, and it doesn't look like you'd be upset about that.
A Christian thing to do is to first of all accept what he is doing. You can only change things that you understand, and only things that you understand you can accept. Right now you don't understand what is going on, so maybe you two need to get closer together. A husband and wife should be the best friends in the world, with no secrets between them, and absolute understanding for each others mistakes, no matter how "big" they are.
Love and understanding that only goes as far as our own shortcomings allow them to go - like jealousy, anger, criticism - is not real love or understanding. There is a lot to learn from this experience for both of you.
If you were to really accept him, and understand that he wouldn't do it if he weren't missing something, the problem would go away.
If he is really "addicted" to porn (which I don't see from your text), then a little help from a therapist could go a long way. But believe me, no man who has a loving, understanding and sexy wife will care to spend time looking at sexy pictures of other women.
Last but not least: religious beliefs are most often used to control people. If you read what Jesus said carefully, you'd see that he always helped FREE people from their own chains of illusions they were living. Do not ever use Christianity to try and enslave another. Help them see the light, show them a better way, but NEVER condemn or judge another. God can judge, and only God. We are not to judge.
"There is so much good in the worst of us, and so much bad in the best of us, that it doesn't behoove any of us to talk about the rest of us."
It would be much better to talk about this problem from the point of YOUR feelings about it, rather then - "he is doing something bad, how to I make him stop."
You don't have to label a behaviour as bad to have a right to be hurt!
You have a right to tell him - hey, it really bothers me that you are doing that. But before I ask you to stop, I'd like to understand both why you are doing it, and why is it bothering me so much. Do you mind talking about it?
See the difference?
God loves him even with his "addiction" and is not judging him. Try to do the same.