I certainly understand that reaction, but I don't think it's crazy.
I just joined one. My primary care physician recommended it. It's about 28% the cost of the regulated ACA plans in my area for my size family. Read that number again. And, it covers everything (except no pre-existing conditions) except for things like cosmetic surgery.
The list of things that the ACA plan didn't cover at all was confusing and pretty lengthy, and it had a $9k deductible (or more, many of the cheaper plans had $15k deductibles) per family member, and double that (two family member's worth) for a max family deductible. To me, that is crazy. And, for the cheaper plans, they required coinsurance, so if I had a disease that would cost $200k, I would owe $67k.
Most amazingly, there's no deductible except for the $400-per-visit deductible. (There's no free maintenance or co-pays or anything like that.) Everything is covered after the $400-per-visit deductible, and there's virtually no maximum. Go to the ER, max of $400. Go for a checkup, probably pay it yourself (unless it exceeds $400).
(One could argue that they should cover an annual checkup, but if it was just a matter of adding $150/year to everyone's plan, what's the point; that's an arbitrary amount that can be budgeted in once you know to expect it. Since it's people of that religion only, some built-in pre-qualification occurs to eliminate people who would just abuse the system.)
These health share non-profit organizations have paid out billions by cooperating and coordinating among their members, and you negotiate with the hospital directly as a cash patient and make your own choice of care and providers.
It's somewhat akin to how a credit union is dissimilar to a bank.
I personally find the idea fascinating and certainly prefer it to forced socialized medicine.