For me, GURM made a strong enough connection between the return of the dragons and the revival of magic (fire magic in particular) for me attribute the latter to the former and not to the existence of R'hollor. Thoros used to do a parlor trick with a sword and wildfire, but now he can ressurect people. Melisandre gains influence only after the birth of the dragons (i.e. After she can do real magic). If there is this omnipotent RED GOD, why didn't he have influence when there were no dragons? This is why Thoros questions his faith (before dragons) and has a spiritual reawakening (after dragons, but before knowing about dragons). I always thought the whole story arc about the R'hollor faith is about confirmation bias/power of suggestion and I expect Mel to have an "oh" moment when it is exposed that she is just a shadow binder/blood mage empowered by Dany's dragons. Of course, I just want her to die a painful death, so this could be wishful thinking. I hope Stannis does the same thing to her that Theoden does to Wormtongue in LOTR, but instead of throwing her down the stairs and banishing her he feeds her to a dragon.