Why does every woman other than my wife turn me on? Am I crazy?

You're not crazy. In fact, this does happen and it even has a name: Madonna Whore complex.

You said: "I think of sex as sort of a "naughty" thing and having sex with my wife doesn't seem naughty". You diagnosed it here, but interpreted it wrong. Sex with your wife DOES seem naughty, because she's the one person on earth you love and are committed to. You don't love random women, so deep down you don't feel bad if they arouse you.

You say you're Christian, but this is vague. The only denominations I'm aware of that send these msgs about sex are Catholic and maybe the super strict Protestant ones. If you got this from religion, this is why so many of us distrust them (esp Catholic). One option might be to switch to a less strict Protestant church.

This may not solve it, though, because these feelings are deeply embedded and might include your parents. In that case, you'll need some counseling. This has the potential to derail your marriage if you don't act on it.

Every one needs variety. It's healthy.

Make the sex naughty... incorporate a fantasy in your mind during sex.

she has become routine,,,,,,,,,grass is always greener,,,,,

You are not crazy, just familiar with your wife. You know her every move. her scent, the way she argues, the things she wants, you are bored with her. Even if she were filet mignon you would tire of having it all the time. She is also available and you can see her nude anytime. Forbidden fruit always tastes the best so you have your eye on what is forbidden. I would add it is an illusion, there is plenty of rotten stuff out there. You may find what looked hot was just a disease ridden slut.

You are.........normal.

Marriage kills desire.

Marriage is simply a bad deal.

I'm sorry the churches didn't tell you this,

But they don't really want you to be happy,

They just want to program you to continue paying taxes and donating to the church

like a good consumer should.