How can this concept of religion be twisted to cult-like behaviors?

So here's a concept of my religion, a fictional one

It is an atheist religion of an ancient, indigenous clan, no gods, no deities, but they simply have the fairies (or seelies in their culture) in mind. To them, fairies are the highest creatures morally, pure-hearted, kind and loving, and so, they strive for a fairy-like society, a society without pain or cruelty, a paradise where everyone loves and cares for all, a paradise that is basically like a larger version of a fairy tribe. And mostly, I have the mediums and druids in mind that are caring, kind-hearted, and they even teach children what it means to be kind, and how to be kind

I wonder, how can this concept be twisted to a cult-like behaviour, cause I feel like this is a perfect concept for an antagonistic, villainous even, force for my story