The diagnosis is that Leftism is (almost) everywhere by now, such that it is the water in which we swim - not least because its basis is in the modern mass media which is everywhere and is the water in which we swim.
A few years ago I wrote Thought Prison which analyzed political correctness (or the New Left, the post-sixties Left of identity politics, group preferences and quotas and the sexual revolution); and traced it back at least to the Great Schism when catholic Christianity divided between East and West.
My interpretation was that the only way to be rid of this cancer was to revert to the pre-modern condition. Another interpretation is that this cannot be done, so the West is doomed.
A further possibility, which has been creeping-up on me for two years or more, is that Leftism is so pervasive that it cannot (even in principle) be deleted, there can be no re-set, because since Leftism is by now almost everywhere and what is more deeply interwoven (including into much of the best and most effective art and thought) so that to try and delete it would be like trying to excise a cancer which has already metastasised all over the body.
If we successfully cut out the Leftism/ cancer- what remained would probably not be viable and would certainly not be desirable.
Is there some other possibility? Maybe.
My idea came from the Mormon Restoration in relation to preceding Christianity. The basis of this is the Mormon belief that from about 100 AD onwards, Christianity underwent a 'Great Apostasy'. As a term, this sounds a lot more negative and damning than it is actually interpreted by Mormons.
The way the idea works in practice, is the assumption that Christianity took a wrong turn after the death or disappearance of the Apostles. For example, it lost some vital doctrines (such as pre-mortal existence) and gained some false emphases and unhelpful metaphysics.
This was not self-correcting; so there needed to be a new prophet chosen by God (i.e. Joseph Smith) who would lead a Restoration that provided recovered/ new scriptures (e.g. The Book of Mormon) and doctrinal clarification (e.g. the Doctrines and Covenants); together with a re-booted priesthood and a church organization suited to the needs of these 'latter days'.
But Mormonism does not reject the previous 1700 years of Christianity - is not hostile to pre-Mormon Christians - does not try to delete it from consciousness or usage - does not try to restart Christianity on the basis of the 'primitive church': quite the opposite.
Of all the serious Christian denominations of which I am aware, Mormons are by far the most positive about other denominations; and up to the very highest level will quote and learn from and revere good counsel from any source and any point in Christian history (and, indeed, from outside of Christianity). This has always been the case from Joseph Smith onwards, and is not a matter of theory - this is a very warm-hearted and spontaneous thing.
In sum, from a Mormon perspective, the Restoration was necessary, but that does not mean that everything which went before could or should be discarded - rather pre-Mormon Christianity (and other modern Christian churches) is subject to addition, subtraction and a different emphasis: but it is not by any means deleted, rather it is willingly, actively and happily used - but selectively.
In a word pre-Mormon Christianity is transcended; or in another word re-framed; or re-interpreted and built-upon what went before.
By analogy, I think it may and should be possible to do the same with Leftism.
Perhaps it is possible not to fight Leftism head-on, in an 'us or them', all or nothing battle unto death; but for Leftism to repent; and for post-Leftism to re-frame, re-interpret, transcend and build-upon Leftism - pick it up and take it in a very different direction (recognizing that it was in error).
After all, this is what we personally do as individuals when we become Christians. No matter how deeply sinful or misguided our lives have been; we do not try to delete our pre-Christian lives; instead we repent what needs repenting, and start from where we happen to be.
That this is possible is core Christian doctrine. Christ came to save sinners; and takes us exactly as we are now: we are saved by accepting Christ; not post-dated until after some micro-surgical process of totally-deleting all our many and deep and ramifying sins.
From that point, we are Christians,but the creative and joyful work begins of embarking on a life of becoming more Christ-like, a life of theosis: striving to become ever-better Sons and Daughters of God.
Where we in the West happen to be, is inside a state of extremely comprehensive and multi-generational Leftism - which is anti-Good (that is: evil), deeply sin-full.
We need to repent, and start afresh; but this will be by building-upon the good of the past,starting immediately, and without supposing that we can first extirpate the evils of the past.
We must, in The secular Leftist West culture, acknowledge that we were wrong; we must start living as best we can in light of what is right - but this is (or should be) an essentially positive and creative agenda: just like becoming a new Christian.