No one was more on the ball than R.J. Rushdoony. The trends he analyzed in this 1976 essay were all but invisible to most observers at the time. It’s taken 50 years for us to see how right he was.
https://chalcedon.edu/resources/articles/march-to-a-dumping-ground
You start with secular humanism, the worship of man; you get rid of Christianity, the worship of All-righteous God; and by and by, with one failure after another, your humanism slides into existentialism, into despair… and your humanism becomes anti-humanism. You also revolt against reality. Voila.
How did Rushdoony see so clearly?
Through the lens of Scripture, and with the assistance of the Holy Spirit.
It always comes down to the two visions Thomas Sowell wrote about: man is basically good or man is basically bad. As Christians we know man is basically evil because he is a sinner.