It's like an inverse-masquerade (i can't spell) party where everyone is no one and we just get to project onto each other who we think they are.
Kind of fun, really. Particularly when you learn how to create an image for yourself so that you are schrodinger's larp… You are both what they project you are being as a representative of that idea… And a larp that is actually not until the FBI serves a no-knock and collapses the front door.
Most people are good. However, trust is something that can and will be abused by those who are evil. Evil will naturally seek positions of implicit trust to allow it to manipulate.
Religions are very old institutions which often command a lot of trust at the center of society, governance, and culture. A society derives morality, law, and justice from its concept of the divine. How many have been convinced to turn the other cheek in the face of abuse and expansion of evil… As an example?
When evil can corrupt and shift the very concept and identity of God in the mind of the public, it can cloak its evils as being the very grace and blessing of the divine.
It should come as no surprise that the Church would become infested with evil over the centuries - if it was ever truly "good" to begin with. This isn't to say that everything the Church has done is evil, or that even the actions of many within it are evil - again, most people are good and will do what they can to perform good acts.
But the institution can be founded and built around evil in a tragic scenario where the bones of an institution are the very evil its flesh fights against.