Millions of people in the United States are fundamentalist Christians who think that the Bible is infallible, the Earth is only a few thousand years old, and Jesus is due to return within half a century or so. Starting in the 1950s, fundamentalists began to engage in vigorous political campaigning against policies like sex education, the legalization of abortion, and state recognition of homosexual marriage.
Why do fundamentalists campaign against these policies, and why did they start doing so when they did? Based on what I have read, fundamentalism as a political movement started in reaction to events like Watergate, the loss of the Vietnam War, and student rebellions on college campuses. They interpreted these events as analogous to when, in the Old Testament, God would pass judgment against Israel for turning away from God, and they think that the only way to get God back on our side is to make our nation as “Christian” as possible.
To this end, fundamentalist leaders like Jerry Falwell and Pat Robertson have developed an enormous media empire dedicated to spreading the message of fundamentalism. Fundamentalists have numerous television shows, radio shows, and websites, in addition to having a collective captive audience of millions in the pews across the country every Sunday. Fundamentalists exert considerable political influence as well. Ronald Reagan, for example, went out of his way to appeal to the evangelical voters, and explicitly said in several of his speeches that he agreed with them on many points, like abortion.
Fundamentalist Christians think that the family is central to the survival of the United States, and they think that the husband should be at the head of the family and that the wife should try to make herself subservient and appealing to him, as the Bible allegedly requires. Accordingly, they generally oppose movements like feminism and the gay rights movement which they see as threats to the family. They were also generally opposed to the civil rights movement, although there were dissenters among fundamentalist preachers on this point.
Just as they think that the Bible should determine family roles, fundamentalists think that the Bible should be the arbiter of our scientific conclusions as well. Among fundamentalists, Young Earth Creationism is considered a legitimate, albeit controversial, scientific theory, and a serious competitor to the theory of evolution.
The odds of routing fundamentalism are not very good, but I think atheists who want to make a difference could try to do two things. First, they could explain why fundamentalism is not intellectually credible. Fundamentalist leaders repeatedly assert in their speeches that fundamentalist Christianity is intellectually tenable, and that is a clear weak point in the movement’s narrative. Second, they could explain why atheism does not imply nihilism or moral decay. As I mentioned above, one of the main concerns of fundamentalists is that abandoning Christianity will leave us without moral guidance, so atheists need to combat that claim if they are to persuade fundamentalist Christians to leave the movement.