That theologically conservative churches are growing and mainstream denominations shrinking is old news. The numbers quoted for a few key beliefs in the WaPo article are interesting but not shocking. The tentative guesses as to why (though I suspect the author is not tentative and is keeping it simple for his audience) are also not original. But... Look at the attached video and hyperlinks between paragraphs that the Post puts in. Only the UMC one is kindasorta on topic, but even at that, it is focusing on the issues a subgroup think is essential, while others would put a dozen issues higher.
Early 1979 was when we last had a TV (16", on a rolling stand), and TV was constantly running in the day area at work. The days of three identical networks. I recall following the election of two popes in 1978, with the newscasters on every station, in every update, speculating whether the new pope could be expected to change the Catholic church's position on abortion and the ordination of women. Those were the only two issues mentioned, on and on. It was as if this was all they could understand. They couldn't imagine other issues being important.
They didn't even know what they didn't know. Recall that twenty years before that, in 1958, 96% of Americans identified with a house of worship, and that only 10 years before, nearly every child was kept in religious studies until confirmation, bar mitzvah, or the denominational equivalent. Announcers on the 3 networks in 1978 had almost certainly grown up with eight years of religious training. It was onto this stage that the conservative preachers stormed in the late 70's. That they were both theologically conservative and politically conservative was not necessary, but neither was it accidental. They railed that they were misunderstood, and that great swaths of the American people were now separate from the values of television.
Hands went up in horror insisting it wasn't true, and these fools, these bigots, these south/midwest/southwesterners were deceivers, oversimplifiers and liars. It all sounds rather familiar. If you enter that discussion today evidence will be marshalled against your claim of media bias. It will be dismissed as a cliche, a mountain being made out of a molehill. Look at how many conservative outlets there are now. Ridiculous.
That same dismissiveness was on display then. Let's review some easily-researched facts about this. There were, as I noted, three networks. Fox News Channel was not up and running until eighteen years later, and was tiny at first; Drudge was about the same time; it was 1988 that Rush Limbaugh came along with his insistence that the mainstream media was biased. He didn't make that up. He didn't talk people into some new-fangled idea. The roaring preachers, and the Limbaughs, and Fox News only announced what was rather obviously true, though consistently derided. The emperor had no clothes. (And believe me, I was derided for claiming it.)
This. This is the background against which denials of media bias are attacked now. Are there conservative outlets? Sure, lots of 'em, things are better. Have the Washington Post and New York Times changed, or the major news outlets? Not a bit, from what I can see. Now their excuse is that they are a counterbalance, a responsible other side to Breitbart and Fox and Drudge. Like the Japanese having difficulty even decades later admitting they did anything wrong in slaughtering millions in China or in attacking Pearl Harbor, the mainstream outlets still have only evasive acknowledgement that they did anything wrong. Does anyone doubt the historical evidence anymore?
You are learning where my biases come from. That's fine.
Given all this as context, what did the mainstream denominations - at least in their official bodies and seminaries - do during those forty years? Easy. They had already started identifying with the culture the media told them were the righteous ones fifteen years earlier and more. They sided with the media and condemned the theologically conservative churches, for the most part. In a thousand small ways they chose who they would stand with. The didn't have to. In fact, the New Testament is repeatedly specific that we should ally with each other and not the tribe that is this world.
They don't like Trump. I agree he is something of a whirlwind. I wish they had not sown the wind. I was Congregationalist and then Lutheran in the years up to 1987, and in an only moderately conservative denomination thereafter. I count myself as an eyewitness. As a result I greet contemporary claims of evenhandedness and openmindedness with considerable suspicion. I am not naturally a nice guy or very tolerant myself, but I recognise an obligation to try and take you at your word and give you the benefit of the doubt. Again. But I grow weary, and I'm not sure I am capable of this anymore.
Prove it. If you want me to believe that you are listening, openminded, and evenhanded, show your evidence.
Or conversely, show me the evidence that it has been the mainstream denominations meeting the wild zealots of the radical right at some half-way point all along, trying to find common ground rather than insisting that your original position is the common ground and being insulting.