The simple story is that the following things happened: (1) Our Judeo-Christian heritage was weakened by the Enlightenment and the Scientific Revolution, (2) The robust cultural confidence of the West was destroyed by the two world wars, (3) Affluence and technology became the new gods that the culture worshiped.
Cultural Marxism would not have had a chance had it not been for these three things. The answer: a return to the roots of our Western culture and a rejection of all the false gods.
What would rejecting the scientific revolution entail?