Leon Thomas spent a couple of years on this video; it is extremely thorough and also a lot longer than what you typically see on YouTube. It is worth your time because the right-wing evangelical movement — perhaps more accurately called the Christian dominionist movement — is the most important component of the far right today, accounting for about one third of all Americans. Not coincidentally, hard-core Trumpers are about a third of all Americans who are eligible to vote.
I took the time to read the first Left Behind novel about a decade ago, and it really does explain a lot of the insanity of American politics. (Save yourself some time and watch this documentary instead.) The only important thing that I feel like might be neglected in the documentary is the relationship between anti-communist hysteria in the US and Left-Behind-style theology; that is to say, perhaps the biggest reason behind that hysteria is that far-right American Christians saw the Soviet Union as an immense atheistic force that intended to convert the entire world to an ideology based on materialism. That characterization is technically true, though certainly inaccurate.
In the minds of US Christians, the conflict between the US and the Soviet Union basically became a battle between the forces of their God and the forces of Satan. That they somehow decided that the UN — which is an agent of neoliberal capitalism — was part of the atheistic goals of communism is curious. The likely reason for this reframing is that American elites purposefully steered the conversation away from the real goal of communism — ending the rule of abusive elites — and toward this religious non-sequitur.
My point here, though, is that the reason conservatives are so terrified of anything they perceive as “Marxism” is because their worldview sees it as a threat to their very existence — quite literally. Fear of death is one of their primary motivators — to the degree that they almost completely sublimate that fear — and a Marxist world all but guarantees that they will eventually cease to exist.