I've had a different view of the Duggars' "faith" than you.
In my opinion, JimBob seized on this particular faith and, in his case, its accompanying cult, for one reason and one reason only: It looked like an excellent tool to shore up his huge but also fragile ego. Seems to me that nothing I've ever heard of them doing conflicts with this view, actually. HIs "faith," just like everything else in his life, such as his wife and children, exists to serve him. Never, ever, the other way around.
I'd love to hear some counterexamples if there are some. And I admit that I say this as someone who's barely ever watched the show. However, I've read about it extensively for years, including acres of recaps.
I do believe that JB believes he's some massively faithful person. He's just that blind and lacking in self awareness. But where is the evidence for his actually following scripture rather than just haranguing other people to do so and parading it about to show others how great he is. They may have a prayer closet, but that's not where JB does his praying. He needs a Senate seat and a tv show.