I came across Colin Wilson's The Outsider (first published 1956) at the age of nineteen, and was astonished and delighted to find for the very first time someone grappling directly with what I found to be the main problem in life.
The Outsider set the pattern for most of Wilson's books in being constructed around multiple biographical summaries, woven about with essayistic passages of criticism, analysis and manifesto. I went on to read many others of Wilson's books of this type.
As I read, I would be in state of excitement, with a feeling of being just about to cross a threshold, achieve understanding, and transform my life for the better - but it never actually happened (indeed, overall, my life was getting worse - my character closing and coarsening).
What usually happens in these Existentialist books of Wilson's is that he will take a writer, artist, philosopher or some such person - and discuss his life and work from the perspective of their understanding of questions such as 'What is life really worth? What can be got out of life by a man with no material worries and no obligations to fulfil?' [Reference is to The Strength to Dream section on HG Wells.]
I still agree that this is among the most fundamental of questions. The revealed preference of mainstream modern people can be seen in what they actually do when in this situation of having no material worries and no obligations to fulfil: they create material worries (by their compulsion to spend so much money) and they create obligations (by keeping themselves 'busy' and boasting about it).
Material sufficiency for almost everyone has been available in The West for more than 60 years; but instead of leading to an increase in existential, spiritual, religious living - it has fuelled a shallowing and trivializing of life by entertainment, distraction and busyness - necessitating a continually increasing surplus beyond sufficiency and driving yet more material worries and obligations.
But having raised such an important question, and having decided to tackle it by a new, and more optimistic, existentialism; Wilson never really came much closer to solving it than in his second 'outsider' book - Religion and the Rebel (1957), where he considered and rejected Christianity.
Wilson had, indeed, created an insoluble puzzle for himself, as can be seen from a comment at the end of Strength To Dream when he calls-for an existential literary criticism. He describes TS Eliot's earlier attempt to create an existential criticism in After Strange Gods as a failure because Eliot refused to discuss the basis of his religious convictions and therefore made his criticisms from the basis of a 'deliberately mystifying dogmatism'.
What Wilson is therefore asking-for is an impossibility - an existential criticism which is also turned-upon-itself. Because all criticism must be from a standpoint or perspective, and if criticism cannot be allowed to proceed until that standpoint or perspective has itself been critiqued, then nothing will ever be accomplished - since no assumptions have been allowed, and any assumption must first be justified - which can only be done by calling on some other assumption/s - which is itself then open to challenge. It is an infinite regress.
This brings me to my understanding of why Wilson never got further with his existentialism than a brilliant diagnosis of the noble failure of other thinkers -- because he denied the reality of a perspective outside of human life. At the bottom line, all deep thinkers are a failure from the perspective of answering 'what is life really worth/' - because they all died.
Mortality - along with the other related problems such as suffering, limited ability, disease, decay - puts an end to all pretensions to have solved Life.
Wilson perceived this to a limited extent, in taking up GB Shaw's fascination with extended human life (eg 300 years) - but more-of-the-same does not solve anything, really - just puts it off. So long as we know we will die and our perspective acknowledges only this mortal life, then we are stuck.
The answer is, of course (as presumably TS Eliot perceived) that we should not be trying to answer the question of the meaning of life from a perspective restricted to mortal life - but from a larger perspective which encompasses mortal life.
In a nutshell, this perspective can only derive from divine revelation - or else we are back inside the infinite regress.
Mortal life can be understood, and its success evaluated, only in light of a perspective which is outside mortal life, which sees it as a whole, and judges it in terms of what lies outside of mortal life. An existential criticism which denies, as a metaphysical assumption, the reality of a wider frame for mortal life, has set itself a formally, necessarily, insoluble problem.
We may term another person's metaphysical assumptions a 'mystifying dogmatism' but that is facile; because it can always be said about any fundamental, bottom-line belief with which we disagree.
The reason that I was never able to get across the line from my excitement with Wilson's defining of the fundamental question, and exploring the possible answers, was that I too (for three decades) shared this 'anything-but-religion' assumption - and saw Christianity as an evasion, a cop-out, a false answer; rather than being the only and necessary answer.