I have been reading Ray Monk's biography of Ludwig Wittgenstein - and found the first part very useful and helpful; but had to stop reading soon after Wittgenstein's return to Cambridge in 1929 with his commencement on revising his earlier views expressed in the Tractatus Logico -Philosophicus (published in 1921)...
I had to stop reading because the corruption of Wittgenstein, and his malign effect on so many other people, became too painful to continue.
My understanding is that Wittgenstein was - until shortly after the 1914-18 world war - a deeply religious man who was on the verge of being fully Christian but never crossed that line; after this time his work was a massive, nihilistic rationalisation of his rejection of Christianity.
Metaphysics was at the root. In Tractatus, Wittgenstein wrote a primarily metaphysical book but made the error of assuming that logic was the basis of all philosophy; this he excluded metaphysics from philosophical communications (he continued, avidly, to speak about metaphysics outwith his philosophical work); not because it was unimportant - quite the contrary, but because it was not part of logic.
In Tractatus Wittgenstein made an arbitrary but unjustifiable decision to assert that on the one hand logic could be apprehended by direct knowing ('seeing) but that metaphysics could not ('saying'); therefore he asserted that logic was communicable but not metaphysics.
But there is no reason why metaphysics could not be directly apprehended in exactly the same way that the basic, atomic propositions of logic can be apprehended; therefore there was no reason to exclude metaphysics. However, this was one point on which Wittgenstein became inflexible - he revised almost everything in his philosophical 'system' but not the exclusion of metaphysics.
For Wittgenstein - nothing knowable was really-real.
Thus Wittgenstein's proto-Christian religion was subverted; because Christianity became merely a psychological state. For example, he repeatedly said to many people that while he respected the Roman Catholic Church (in which he had been brought-up) he 'could not' believe all the necessary parts of doctrine.
Wittgenstein seems on the one had (by his repetition of it) to suppose he has said something profound here; yet also seems to be unaware that his personal inability (on a particular day) to believe in something is what is truly subjective; and that the proper question was whether or not that 'something' is true, is really-real!
(Who cares what Wittgenstein happens to think today about Transubstantiation? He often changes his mind! - The proper (metaphysical) question is whether Transubstantiation is a reality, or not? The exact answer 'yes' or 'no' is not (in my opinion) essential to being a Christian; but any Christian must regard this question as a matter of being about-reality, not of being about-individual-human-psychology.)
As a further, and deeper, example: Wittgenstein in his early life correctly recognised that true Christian loving-faith 'casteth out fear'. He was deeply fascinated by accounts which showed that deeply faithful Christians were not worried about the future, about what 'might happen'...
He saw that fear is, in a deep sense, the opposite of love: if we truly believe in the Christian God (creator, god of love, personally concerned by us his children) then there is no ultimate reason to fear anything.
But, Wittgenstein came to regard this 'fear' as a psychological state purely! When the proper understanding of evil-fear is a kind of existential angst; the fear that is cast-out by faith is not merely a human emotion (which in this mixed world is unlikely to conform to any ideal) but the ultimate assumptions concerning the nature of the world.
It is, most exactly, metaphysical fear which is cast out - it is the assumption that fear has a necessary place in our lives that is cast-out by Christian love, by faith in the loving-nature of a creator god.
Wittgenstein went from rejecting speaking about metaphysics in his early work (Whereof
one cannot speak, thereof one must be silent." were the final words. The error is in the word must.); to rejecting all possibility of metaphysics in his later work - in which everything reduces to (current, evanescent) psychology, to therapy, to 'usefulness', to 'life' (to 'language games').
Wittgenstein made it impossible for himself to become a Christian; and thereby damned himself and everybody else who took him seriously and deeply. He also made many people (especially those closest to him) very miserable in this mortal life (and did not seem to apologise, repent or even notice the fact; unlike earlier in his life) - consistent with demonstrating that the exclusion of metaphysics does have distal consequences.
And that is why the second half of Wittgenstein's biography is too painful for me to read...