I think your analysis is wrong, as is evident by the changing morality of this country. These folks that have given up on "Churchianity" have also given up on Christianity.
I can give you personal insight into this....
I agree the changing morality in this country has most giving up on Churchianity. But not all. But many are not even aware that they, in truth, have given up on Christianity and that is because their churches do not preach or teach what God says....
2 examples from my own life that I have known.....
A man who is from Ohio. Had been in prison for attacking the man he walked in on while the man was doing unspeakable things to the wife and 16 year old daughter.
Then , it was not this that he went to jail on until
he tried to get sole custody of the daughter, after the divorce, and then the man who was attacked brought charges with the ex wife AND daughter as witnesses.
Well.. this "partisan" religious believing person is very Roman Catholic. Goes to mass
every Saturday night, Makes appointments to go and say the Rosary to a priest from time to time.... You get the idea....
He is not looking to marry again because he trusts no one and never another woman again... but would like to get it on with me, if not in person then a rousing session of online .........
He does not relate anything physical as wrong.
A gentleman (?) who wrote to me by way of a pen pal site, just this past week.
After I first said I was a Christian and also a Trump supporter we got into how great POTUS is and he also said he was very much a Christian to the point he is in church every Sunday
, bar any unforeseen circumstances. He never said and I did not ask which one. He lives north of Dallas.
Then, because he never said I asked if he was married.....
The story I got was he is separated. She currently is living with her mother in AZ.
Then he said he was not looking to change that. He would never marry again.
But shortly after they married in 1983 (Might be off a year) she changed in the bedroom department from what he had assumed was his perfect mate because of dating and pre wedding playing around and then 9 years ago she moved to a separate bedroom.
He further says that drove him to an affair and she knew about it but refused to divorce as she does not work and wants to be kept.
Her dad died a year ago and she went to stay with the mother this past year but he feels she will be back home sooner or later.
He said he never wants another in person affair but wants the online ones ... (I cynically am thinking he is a cheap skate)
I said no and he has not responded.... thank goodness.
But this is another example of one who is into church but without a clue to what he is wanting is wrong.
And I do blame this on the churches ( Partisam Religions) for not teaching as they should.
They need to get back to the hellfire and brimstone sermons and if they lose most of their congregation at least they will be right with God and so will those congregants who continue to attend.