How do whole religions fall away?
Here I will look into just one of these mechanisms.
In Acts 20:29-30, Paul mentions two threats - predators from outside, and people arising from within to draw disciples after themselves. These are related. The predators from outside, deceiving people and ripping them off, inspire leaders to say perverse things to draw people aside after themselves - to keep them safe from the dangerous outsiders. And these guys are the ones who, relying on man's authority, and on doctrines imposed through intimidation, protect people from pursuing the truth under God's guidance, because people will be deceived that way. They have to be deprived of freedom to keep them safe.
The Grand Inquisitor in the Brothers Karamazov, who kills Jesus in order to keep Jesus from disturbing the pure religion that he is defending, is just who Paul was talking about.
The people who have lied to the American people and systematically destroyed the Constitution and republican liberties supposedly to keep us safe are also the same type. America has fallen away from its secular faith in the same way that Christianitry has fallen away from Christ. Paul said it all in Acts 20:29-30.
It turns out that the only real enemies of the US Constitution are domestic, not foreign, just as the only real enemies of the gospel are the apostate leaders of the churches and their people who love to have it so.