That could be part of it too, but the “it bleeds, it leads” media landscape is a huge part of the problem here. There is a narrative that the media is eager to push, and it’s that the GOP is the religious party, and that the Democrats are anti-religious party. But it’s incorrect and ahistorical. But it also plays into the media inability to call out white supremacy.
Again, that’s in part a problem of the media. As long as they are pushing that narrative that conservatives are the only real people with faith, then that’s what they are going to pursue and present to us. The ideology is hard to break, but we have to get past it, or else we risk letting them win.
But again… Why should we let a minority eager to spread bigotry dominate our understanding of what’s happening? 
Should we call out the bigots and religious assholes, whoever they are? Absolutely (and this includes bigots among atheists, of which there are none too few). Should we let that dominate our understanding of facts, and lump everyone of faith into one big group? No.
