It is based on Critical Theory. Critical Theory came out of the Frankfort School in the early 20th century. The Frankfort school is where all modern Marxist ideology comes from. It was first posited by Max Horkheimer in 1937 in his essay "Traditional and Critical Theory".
The ideas of the oppressed and the oppressor in Critical Theory have been changed from the business owners (aka the rich) and the laborers to whites and primarily blacks and, as political necessity dictates, other non-whites.
The idea is pit all races against whites to further divide and destroy America. It is being done because the traditional approach of Marxism was not working. Because so many people can and do own their own homes they care less about the rich getting richer. Only the left has made a mountain out of a mole hill about the rich getting richer.
In a free market system the rich getting richer would be a good thing because it would mean that all economic levels would also be getting richer, a situation that cannot happen with any other economic theory.
The problem with Critical Race Theory is it has to make every white person a white supremacist in order to work. There is a massive huge problem with that. We're not white supremacists. Not even close. Maybe about 0.01% of white America holds that belief. While the attack is directed at whites the bigger picture is Western Culture and specifically the Judeo/Christian morals. That has been the goal of Marxism from the beginning. Marxism cannot have a belief in a supreme being because it places the central planners or government at the level of a supreme being.
In the Judeo/Christian morality comes freedom at the individual level. Marxism cannot abide freedom at that level. Every Marxist on the planet will disagree that statement but the fact is what Marxists believe in is collective liberty. Liberty at the group or collective level, i.e. women's rights, black rights, gay rights, etc. However, America was founded on the idea of individual rights and that those rights are inalienable and cannot be taken away. They do not come from man or a government, they come from our Creator.
Critical Race Theory is the antithesis or Martin Luther King Jr's I have a dream speech. No longer are people judged on the content of their character but solely on the color of their skin.
And if you disagree then it is YOU who does not fully grasp what CRT is.