J.N.
I went through that with my son. I finally got fed up with it just before he turned 4. (We'd been trying for over a year, too). He's a stubborn kid, and this is a battle mom can't win.
We put him back in diapers, and took away one of his favorite activities (it was video games). We said it was a "big-boy" thing, and big boys go potty.
Then we completely dropped the subject. Didn't bring up potty at all, unless he asked for video games, and then reminded him it was for big kids. (His older sister still got to!) We left it at that for about 4 months. Then I said "do you want to try going potty again so you can be a big boy and play video games?" He said no at first, but changed his mind. Used CLOTH training pants. Once he was on board with it, he was 100% trained (no accidents except the occasional normal kid oopses) within 2 weeks (closer to 1 I think).
It sounds like yours is also a power struggle. He knows that you can't make him go potty, and he just doesn't want to play along with your attempts. Let it go long enough that the game is over. Try to hang out with other kids his age who do use potty (peer pressure can be good! - and they don't even say anything to each other). Try again in a few months, but don't say anything (or very little) in the mean time.