> How did they get so far Left so Quickly? <
That’s a good question. The party of Truman, JFK and even Carter differed from the Republicans only by degree. You could be a law and order guy - and a believer in the value of honest work - and still be a Democrat.
Not any more.
Harry Truman and JFK would be harshly unwelcomed by Democrats today.
You’d be surprised how many church-going Bible believers remain stubbornly Democrat.