Your problem sounds so familiar to me--I have a son who resisted naps for so long!
Here's what I decided to do after realizing I just couldn't go on without naps (and neither could he)...
I try to do an abbreviated version of the bedtime routine. For bedtime, we read several books, then lights out, prayers and I sing "Jesus Loves Me" (he still nurses for the song part).
At naptime, I read fewer stories, then lights out, then I sing "Twinkle Twinkle Little Star" and "Mary Had a Little Lamb." He doesn't nurse at naptime.
I was having trouble with him waking up once I'd put him down in his crib after singing at naptime. (He is drowsy but awake both at night and at naptime.) Then I realized, when I put him down at night, I whisper that I love him and will see him in the morning, and give him a kiss. So I started doing that at naptime too, except saying I'll see him when he wakes up from his nap. That totally did the trick! So try to stick as closely to the bedtime routine as possible. You can vary a little since it's naptime, and he'll know the difference, but try to keep those same comforting elements there so that he can learn to fall asleep just like he does at night. Good luck.