From 1956 onwards; Colin Wilson identified the prevailing pessimism of the Western intellectual class - writers, visual artists, philosophers etc - and concluded it was rooted in negative basic assumptions concerning the nature of reality.
Wilson went on to argue - I think convincingly - that if more positive and optimistic assumptions were instead adopted, then human life would be more enjoyable and worthwhile. Some other more or less influential writers said much the same - such as Abraham Maslow.
This is a pragmatic argument - in the sense that it is not based upon the truth about the world (neither Wilson nor Maslow believed in the reality of God) but based on the assertion that life will be better if you believe so. The same type of argument was used by William James around 1900, Robert M Pirsig in 1974, or Richard Rorty.
But this did not happen. Pessimism prevailed. Mainstream basic metaphysical assumptions asserted (inter alia) that the universe, life and consciousness all happened by accident - and were not headed in any particular direction; the spiritual realm is a fiction, there is no soul, and death is annihilation.
In the context of the already-existing Western culture; pragmatic arguments made no significant difference because believing and acting upon them they carried a penalty. First condescension and disdain - i.e. low status). Then material disadvantage; because professional success was optimized by conforming to the prevailing ideology, artistic and philosophical success to extending the successful trends.
In a twentieth century context, when confronted with tough decisions - when long term possible benefit was blocked by immediate term disadvantage - pragmatic, un-rooted optimism was just too weak.
In other terms we can observe that the demonic powers were getting a grip on Western culture from even as early as the 19th century; and increasingly 'rigged' things such that pragmatic optimism was discouraged, yet unthinking, habitual pessimism prevailed.
Pessimism was simply assumed and adopted spontaneously, while the onus of proof was on optimism. When the justification for optimism was merely pragmatic, then this was regarded as equivalent to admitting it was "made-up because I am too weak to face the bleakness of reality".
Colin Wilson was cheerful by nature and largely immune to cultural trends, however this applies to few people. Most people will only be optimistic when they believe it is based on truth - on reality.
Which means that when culture is more and more against us, we can only be optimistic when we believe in the reality of a loving personal God, and that joy and fulfillment are possible (and can be ours) outside of this mortal life and finite planet.