Liberals have had “religion” for a looooong time.
The atheistic “freedom from religion” garbage in relatively recent legacy from Communism, and took hold in the 1960s.
Before that, a lot of “Liberalism” and “Progressivism” was actually driven by a perverse form of Christianity.
Yes. The Puritans became the Congregationalists, later the Unitarians. Transcendentalism was an off-shoot of this line. What they all have in common, despite the changes in doctrine and concepts of morality, is that they have all felt a smug superiority of self-righteousness and a demand that everyone conform to their “morality” (though these days that morality has morphed into political correctness). This group had the first public schools in America, which on its face is laudable, but it was also another tool in indoctrinating everyone into their personal vision of morality. That’s one thing which has certainly not changed. It’s notable that these denominations come mainly out of New England, which has also been a breeding ground for various political correctness movements.