Why is public nudity such a taboo behavior, not only in the religious community but society as well?

The modesty asked for by religious communities is bound up with attitudes about sexual display. In some communities, it is about promoting the idea of equality despite the differences of gender, race, and class.
It is just not about one set of beliefs or cultural norms. It is wired into why there are norms.

Clothes are more practical in Northern latitudes for races who lack pigment and to keep warm. Humanoid species lost their hair for some reason and this increased the practicality of a manufactured cover to protect vulnerable parts. Even in more benign equatorial latitudes where nudity in hunter-gather groups might be more common (sans Western influence) covering genitals might make sense.

Current inherited customs likely grew around a very basic practical need for clothes while engaging in physical work.

If you dug into game theory there might be some sense in which clothes actually perform some kind of Evolutionary Stable Strategy (ESS) function on par with "poker face" type behavior in animals. The less you show in terms of weakness or strength the more you stand to gain when deciding how to act against a competitor or collaborator. It levels the playing field of first impressions.

To some extent the severity of the taboo for any of us is an accident of history. The larger and more sophisticated the society, the more stratified it is by status and property, the more severe the customs imposed are out of a need to maintain order.

This practice is obviously very meaningful and important to you and your wife. What does public nudity deliver to you emotionally, spiritually, physically, or psychologically? How does the practice affect the quality of your relationships with people generally, outside your circle of like-minded nudists? And what would you identify as the most common misconception most people have about public nudity?

Reply to wertwo I think you were overly optimistic!

I don’t see it becoming accepted within the next century. Possibly ‘laws’ will be loosened to some degree. I can imagine, as there are now, more widespread instances of nudist beaches - meaning having festivals that were something like a ‘celebration’ of the human body (something akin to renewing the ancient Greek games).

There are so many interesting societal habits and rituals we could talk about here.

Reply to wertwo
I rather suspect that the machinations of democratic politics would be better effected if parliaments, congress etc were conducted in the nude.
Would you agree?

Quoting A Seagull

I rather suspect that the machinations of democratic politics would be better effected if parliaments, congress etc were conducted in the nude.
Would you agree?

Now that would be one of the few things I would like to see televised. Those, what would be a polite way to say shitheads, would be moving things so fast the parliaments, congresses of the world would only need to convene for a couple of weeks a year. Look at all the money that could be saved.
Best idea I have heard in a long time.