It goes both ways. I have seen absolute con artist sell soggy moldy hay at a premium and complete idiots who had no idea Queens Ann’s Lace and thistles is not hay. Only thing in common is the fool buying it.
However in this case I tend to lean towards the latter. A “Horsey Church”, are you kidding. As far as donations go, to qualify as a donation we are required to place “suggested donation” on anything that we do for fund raising. Which means if they drop a quarter in the till, you gott'a give it to them. “Selling” for “profit” is strictly prohibited. You will lose you tax free status licitly split (n’other reason to think they fall in the not so smart category). If they are indeed selling for profit then yes it should be taxed (not that I am a fan of IRS).
I spent years in church and I know exactly where I stand with my maker. Very few and I mean “VERY FEW” established religions are even close. Most have some “special” thing no one else does and that’s why they are right. Religion is like the Constitution, simple, if you have to “justify” it, you probably shouldn’t be doing it.