The term "Political Correctness" was hijacked by right-wing ideologues in the late 1980s to trivialize and disparage concern for basic human rights for people whose race, gender, ability, size, or other attributes were inconsistent with the norms established by straight, White, Christian men.
Before then the term was seldom used other than among Leftist to discuss political ideology.
The idea of claiming there was a Culture War by liberals and leftists against America was formulated over several years by right-wing ideologues Patrick Buchanan, William Lind, and Paul Weyrich.
Of these it is William Lind's development of the idea of a Culture War led by "Cultural Marxists" using "Political Correctness" that incorporated antisemitic conspiracy theories and made of Lind an hero to Norway mass murder terrorist Anders Behring Breivik.
Breivik not only cited and quoted Lind on the subject, but plagiarized whole section of a Lind manifesto.
It is Weyrich, however, who lays out the case in clear prose:
February 16, 1999
..."I am in the process of rethinking what it is that we, who still believe in our traditional, Western, Judeo-Christian culture, can and should do under the circumstances. Please understand that I am not quarreling with anybody who pursues politics, because it is important to pursue politics, to be involved in government. It is also important to try, as many people have, to re-take the cultural institutions that have been captured by the other side.
But it is impossible to ignore the fact that the United States is becoming an ideological state. The ideology of Political Correctness, which openly calls for the destruction of our traditional culture, has so gripped the body politic, has so gripped our institutions, that it is even affecting the Church. It has completely taken over the academic community. It is now pervasive in the entertainment industry, and it threatens to control literally every aspect of our lives.
Those who came up with Political Correctness, which we more accurately call "Cultural Marxism," did so in a deliberate fashion. I'm not going to go into the whole history of the Frankfurt School and Herbert Marcuse and the other people responsible for this. Suffice it to say that the United States is very close to becoming a state totally dominated by an alien ideology, an ideology bitterly hostile to Western culture. Even now, for the first time in their lives, people have to be afraid of what they say.
This has never been true in the history of our country. Yet today, if you say the "wrong thing," you suddenly have legal problems, political problems, you might even lose your job or be expelled from college. Certain topics are forbidden. You can't approach the truth about a lot of different subjects. If you do, you are immediately branded as "racist", "sexist", "homophobic", "insensitive", or "judgmental."
Cultural Marxism is succeeding in its war against our culture.