One of the few truths that I personally hold to be self evident is the concept of equality, as espoused by the author of the Declaration of Independence and the Framers of the Constitution of the United States. That we as individuals [initially meant for white male property owners, but later expanded and applied to all] have a right to life, liberty and the pursuit of happiness, and that We the People are our own sovereigns, as opposed to the throne or the altar, were bold, and yes, pernicious ideas in the 18th century.

Sovereignty over our own persons, both mind and body, is not a negative that of necessity leads to a rejection of expertise, experience and authoritative knowledge. That said, the freedom to choose does not ensure wisdom in decision making. Some choose to join up with a questionable group.

It is the tribalism you’ve described which I find truly pernicious. Tribal truths become doctrine, and the behavior of tribes much like a religion. Peer pressure and tribal identity often overcome one’s own epistemological individualism, and the results can be widespread and catastrophic. Personally, I would be much happier with a little more introspection and self examination over surrendering one’s epistemological independence to a tribal identity.

“This above all: to thine own self be true,
And it must follow, as the night the day,
Thou canst not then be false to any man.”

Thank goodness for epistemic individualism because individuals can exercise their own autonomy and decide what they want to believe or not believe. The so-called scientists, scholars, journalists, etc., are humans with imperfections and biases. For example, I would not take serious a scholar in gender studies or someone with a PhD in theology. Also, it seems to me that you are trying to criticize postmodernism, which came out of academia during the 1970s with scholars like Michel Foucault, Jacques Derrida, and Jean-Francois Lyotard. Postmodernism attacks meta narratives and language itself. Individuals carving their own niche are what has made this country great. So what are you wanting to replace individualism with? Brutalist conformity.

"The fanatic is perpetually incomplete and insecure. He cannot generate self-assurance out of his individual resources -- out of his rejected self -- but finds it only by clinging passionately to whatever support he happens to embrace. This passionate attachment is the essence of his blind devotion and religiosity, and he sees in it the source of all virtue and strength.... He easily sees himself as the supporter and defender of the holy cause to which he clings. And he is ready to sacrifice his life." - Eric Hoffer

“Give people pride and they’ll live on bread and water, bless their exploiters, and even die for them. Self-surrender is a transaction of barter: we surrender our sense of human dignity, our judgment, our moral and esthetic sense for pride. If there is pride in being free we are ready to die for liberty. If there is pride to be derived from an identification with a leader, we grovel in the dust before a Napoleon, Hitler or Stalin and are ready to die for him. If there is distinction in suffering, we search for martyrdom as for hidden treasure." - Eric Hoffer

Your description of individual truths for Americans is exactly as I see it. The people I have met from foreign countries seem to have the same tendency. I think what you describe is universal and not just American. Perhaps in America it is more open and less hidden because of our constitutional rights.

I am an identical twin. Her tribe believes in God, the current trump gop version of republican "democracy", Dr. Fauci helped create the COVID-19 virus and Hillery is trafficking children for sex. I believe her bull shit meter broke years ago.
I have a pretty functional bull shit meter, quit going to church when I was 12 and was over joyed to find this site. Our Dad was raised Catholic but left the religion and any idea that he should as the youngest male (6 kids in the family) become a priest. He was atheist/agnostic and thought the Bible was a good story.
Dialog with my sister is frustrating and sort of sad.

I heard a reference to a movement based on this idea in an article I read. That was the only time I heard mention of it, so I know next to nothing about it.

So drinking a deadly poison because you "know" it will not hurt you is "true?"

Sounds like the cult mindset.

Snake-handling, poison drinking, church members still die.

Facts are not subject to true/false subjectivity.

The obnoxious prosperity gospel is a good example of the greed that permeates society.

You are correct. American culture has always been infested with extreme libertarianism. At different times in our history that has become a great problem.

Impersonal scientism is no less a problem. All not in pursuit of objective truth is devalued: ethics, fiction (literature), or subjective personal experience. In the parlance of Critical Theory we see an overbearing instrumental reason where people themselves are objectified and made into means and not ends in themselves.

One need only look at the Tuskegee and Guatemala syphilis research programs to see this tendency in action. Most people are unaware of the horrors perpetrated in Guatemala. Or consider the use of disabled children at the Willowbrook State School for hepatitis experiments.