It's not a "theory," it's fact. Those who are most intimidated by it, are those who don't want our children to know that this country was first built on the backs of slaves (human beings owned like property) then continued through a systemic suppression of rights and equal justice through things like Jim Crow laws and more lately, by targeted voting laws. All too many either still harbor a false sense of superiority by the luck of the draw being born with white skin, or give their support to leaders who make it clear that is what they believe. Our children should be taught the truth, such as the fact that when our supposed infallible forefathers did not really mean "all men are created equal" - as they did not include blacks or women. Why are some people so scared about teaching our country's almost 250 years of unequal opportunity and the injustices of the law toward blacks in particular (and are trying to redefine the definition of CRT)? Never mind, that was a rhetorical question, as can easily be seen in so many aspects of our current lives.
critical race theory | Definition, Principles, & Facts | Britannica
" based on the premise that race is not a natural, biologically grounded feature of physically distinct subgroups of human beings but a socially constructed (culturally invented) category that is used to oppress and exploit people of colour. Critical race theorists hold that the law and legal institutions in the United States are inherently racist insofar as they function to create and maintain social, economic, and political inequalities between whites and nonwhites, especially African Americans."