“The idea is presented that there is a vast, well-funded, and powerful network of people who will seize the day after the election to create an America that is forever stuck in the racist, sexist, dystopian 1950s.”
In fairness, this really is a ridiculous idea, though not for the reason OP claims - American Christianity is a tangled web of dozens of sects that all consider each other to be at best misguided and at worst raving heretics, so the idea of them all coming together under one banner as an overwhelming army is laughable.