"Some, if not all of the friars, indulged in flagellation ceremonies concerned with mortification of the flesh."

Hmmmm... Either you don't know what flagellation is, or you don't know what indulging is.

Megan: I suppose mortification is SOME folks' idea of indulging.

Me: Maybe the "indulgent" part is that good feeling you get (I assume) when you stop.

Megan: If you're Catholic, it could lead to indulgences.

Me: If you still need indulgences after indulging in mortification of the flesh, you're not very good at mortification.