It's very tempting to use the religion card for naked activities, but this is flawed. Very few people actually say "we believe" being naked is good for you, and so forth. I think this approach stands up fine against some legal challenges and is a good position from which to defend general attacks in principle. If it's ok to go to school wearing a burka, then it's ok to go to school naked, and so forth.
However, nudism/naturism/naktiv is not a religion, it's a lifestyle choice, far more in the mould of being gay. People don't "believe in gay", they just are, or are not. Or choose to be, or not, as the case may be. In some ways I personally regard this as an unfortunate parallel, but that's not the point. The crucial point is to see how the gay movement got to where they are now and how naked people can leverage that strategy. Essentially they did it by "coming out", and saying: "I am gay, get over it."
This is what nudists in every club, naturists the world over, naked and active people everywhere, need to come to terms with. How to promote their lifestyle, whether in private or in public, as a perfectly harmless and entirely acceptable form of personal expression. The traditional private club movement has had over a hundred years with which to convince the world that nudity is acceptable. The situation we are now in, where censorship of nudity in mainstream media is the norm, and nudists are the butt of nudge-nudge wink-wink, jokes, proves they have comprehensively failed, and to move forward we need to implement a different strategy.
What naked and active people, nudists and naturists, need to do, is to "come out naked". This amounts to saying "I am naked, get over it." No more, and no less.