Oh goodness, I wasn't expecting the renewed interest in this thread!
There are definitely some things I'd like to rewrite now that I'm more knowledgable about the community (and also less repressed), but unfortunately it's been so long that the option for me to edit this thread is long gone.
I still stand by a lot of these sentiments and hope that this is a helpful guide for those who are just finding out about therianthropy from a secondhand perspective, but I think I should have been less heavy on the "it's purely psychological" side of things.
Therianthropy does indeed have a spiritual aspect for some/many people -- not all of course -- but it's nothing close to a cult or any kind of damaging belief. On the contrary, the beliefs associated with therianthropy are usually very healthy and mundane. The concepts of souls/spirits, connection to nature, and reincarnation are widespread among all kinds of religious, spiritualities, and non-religions, and are even present in abrahamic religions like Christianity and Islam.
I think the main thing I wanted to point out in my thread, is that the modern concept of therianthropy is not analogous to the old werewolf/transformation rituals you'd find on late 90's - early 2000's internet. Nobody here is touting that you should eat poisonous plants and howl at the full moon to travel to the werewoof plane and 'become' a therian. Concepts and rituals like that are actively shunned in the therian community nowadays, and therefore parents shouldn't need to feel concerned about unhealthy or dangerous influences!
Chances are, your loved one's experience with therianthropy is harmless, and expresisng it is likely even healthy for their wellbeing.
- Fern