All religion is declining in the US.
Much of what passes for conservative "religion" in the US is right-wing politics with religious trappings. Same with what remains of liberal "religion."
Say what you want about them, at least the secular liberals (and secular conservatives, for that matter) aren't pretending. There are plenty of individuals all over the political spectrum who have sincere religious commitments - I have befriended several on this very forum - but when you are asking about trends in a country of well over 300 million people, the answers are necessarily generalizations.
Televangelists are in it for the money.