[Groundhog]

I think this is one of those things that is hard to show in the series with about 5 minutes to dedicate to it each week. What I imagine we're supposed to think is that the High Sparrow has complete sway over the population within Kings Landing right now, and with the King basically making himself level to the church, he's Westeros' version of the Pope.

I think it's happened a little too quickly without enough screen time to feel legit (although it felt a little forced in the books to me too), and I don't really find the nobles reactions to it 'realistic', or at least not in character. I think he would have been snuffed out a lot earlier than now, even with how bad things have been int he capital since the first season.

Having said that, the argument could also be made that this is no different from what's happening with the Red Woman and her faith, the dragons, the white walkers, etc. but it's a more mundane type of religion, faith instead of magic.