The dogmatic economic chasm is the difference in economic and political governance between the extreme right and moderate left/center; an example is the extreme right wing idea that a tax cut for the wealthy is good for the country vs. the moderate left/center idea that income inequality is really at the root of slowing economic growth in the U.S. It is my opinion that the extreme right wing position is delusional and that the problem of income inequality is objectively obvious. Please note that I have not mentioned policies that could address this problem but instead only identified what I think the underlying problem.
The second aspect of U.S. tribalism in a sense is more important in my opinion; people of good will could be in error on economic policy - it is not an exact science. A person of good will can be excused for getting the economics wrong. The second, more important aspect is a question of moral values. Simply put, the extreme right has a thread of racism/intolerance/sexism/greed running through it. Those "right wingers" not in that camp reject these "values" can include otherwise economic dogmatic right wingers, such as Jeff Flake or John McCain or George Will, etc. They can be "forgiven" for their "errors" and be bargained with, one could hope. They are not loathsome. I would say they are simply wrong in their economic opinions.
However, here are the moral issues that a large segment of the extreme right and the President's supporters accept, embrace and promote:
Racism (birtherism, anti-immigrant sentiment, White Nationalism and Supremacy, etc.)
Intolerance (Islamophobia, Christian fundamentalism and privilege, homophobia, anti-transgender bathroom bills, etc.)
Sexism (acceptance of sexual assault, pedophilia, male chauvinism, etc.)
Greed (cutting taxes for the wealthy and rich corporations while not funding CHIP, and threatening to end Obamacare with no replacement, cutting Medicare, Medicaid and Social Security to pay for the tax cuts for the wealthy)
These last items are MORAL issues; they are about right and wrong in the sense of harming or helping actual people directly. A morality that is divorced from actual harm or well being of persons is a useless morality even if it is claimed it is the supposed "word of god." Acceptance of obvious harm to many others in the name of a dogmatic belief (such as religion, tradition, dogma or "free markets") is USELESS.
And here is the embodiment of the moral rot that is at the core of the tribalism in the U.S.: former senatorial candidate Roy Moore, supported and endorsed by the Republican Party and the President as well. He stands for every immoral position listed above and he was the candidate of the extreme right, the Republican party and the President. I can forgive economic wrong-headedness, but the immorality of Roy Moore and those who supported him is unforgivable and cannot be reconciled with people of good will. This tribe of moral indecency MUST be opposed.
This leaves us to ponder our options for the future; we must consider working with all those who support moral decency even if their economic policies are not ideal or are even what we consider "wrong." We must now have a "Coalition of Decency" and work of people of good will with opposing views on non-moral issues. We cannot afford to lose otherwise.