Christian fundamentalism has always presented itself as a morally superior group in direct touch with God, following the Bible, and at war with secular society.
What aspects of society they want to defeat may vary. In the early 1900s they were obsessed with Jews, evolution and immigration. As such they formed the backbone of the revived Ku Klux Klan.
The moralistic fundamentalist was, however, largely a Democrat and even sometimes a Progressive. People forget the Progressives and the Democrats were quite openly racist at the time. The most successful fundamentalist in American politics was anti-evolution crusader William Jennings Bryan, who was the presidential candidate of both the Democrats and the Progressives.
By the 1960s fundamentalists started abandoning the Democrats as the party moved toward acceptance of civil rights for black Americans.
Evangelist John R. Rice, the editor of the voice of fundamentalism, The Sword of the Lord, warned: "It is better for both Negroes and whites to run with their own kind and intermarry with their own kind. The mixing of races widely differing is almost never wise...Thus if a girl would do wrong to marry a Negro boy, she would be wrong to keep company with him, mixing regularly with him in social life."
To Rice, who spoke for the majority of fundamentalists of his day, integration was a communist plot where "hotheads in the North advocate using armed forces to compel white people and colored people to send their children to the same schools, while in the South, leading men in the government and out have banded themselves together to avoid what they think would result in intermarriage and the mongrelization of the race and the breakdown of all the southern standards of culture."
At each stage of their campaign they presented their prejudices as if they were gospel. Since they hated Jews, blacks, Mormons, Catholics, immigrants, God hated them as well, or at the very least, would tolerate them if they kept to their assigned place in society.
Fundamentalist politics was always a combination of two things: hatred for groups they targeted and their own moral superiority. They were "God's people" in direct touch with Jesus and following divine orders. They were redeemed and forgiven and all others were filthy sinners unworthy of respect or rights.
The moralistic cloak was used to cover the true source of their activism--their animosity and contempt for groups they targeted.
They succeeded in taking over the Republican Party and turned it away from Goldwater's view of limited government, into one of Big Brotherism in the name of Christian morality. The problem was their version of morality seemed focused more on individuals private sex lives then on how we treated one another. It's hard to discuss "love thy neighbor" when one is scapegoating Mexicans, gays, Jews, Catholics, Muslims, or others.
At the very least they worked to disguise their own hypocrisy. Those of us who escaped Christian fundamentalism know what a moral cesspool it is. My Christian high school was run by the largest fundamentalist church in America. The pastor had a long-term relationship with his married secretary and housed her a few blocks from his own home. His son, who became a pastor, was caught having affairs with multiple women. The pastor's son-in-law took over the church and then went to prison for seducing an underage female who came to see him about being the victim of sexual abuse. Yet, the principal of the school was the man who got Jerry Falwell to start the Moral Majority.
But now it seems these people are willing to chuck all pretense of supporting morality and focus exclusively on their prejudices and hates.
What they see as God's Own Party, the GOP, has nominated a man who is utterly amoral. Republicans in nominated Donald Trump abdicated any right to assert they defend "traditional morality" or common decency.
Their candidate makes lewd remarks about him sexually assaulting women and, instead of being horrified they make excuses. I've seen Republicans claim it doesn't matter since Trump was a Democrat at the time, others have tried to justify it by saying Bill Clinton was a philanderer. Trump's excuse was he's heard Bill Clinton say worst. But Trump and truth aren't exactly on speaking terms--no matter what the topic.
Jerry Falwell's heir, his son, is sticking by Trump and so is the ultra-fundamentalist James Dobson, who has spent decades attacking gay people for their supposed immorality. Fundamentalism has always preached a morality they want imposed on others, but when they are caught rolling in the mud, it's one excuse after another.
Morality in fundamentalist circles is merely a blunt weapon used to beat others over the head; it is not something they ever apply to themselves. Their morality is a weapon to be used against others, not a guidepost for their own lives.