It was always an element of Leftism, but from about the middle 1960s, anti-Christian, anti-traditional, anti-functional and anti-biological concepts of sex and sexuality became a recurrent and core strategy of Leftism.
As a young Leftist; I personally found this strategy difficult to take seriously - and that was because I was of the Old Left persuasion, that regarded politics as properly concerned with economic and social arrangements.
I failed to notice that Leftism lacked any genuine socio-political-economic goal; and was of-its-nature subversive, oppositional and intentionally destructive; and for this purpose sex/ sexuality is an ideal tool.
(Although the Left also has several other tools of similar value, including healthism, antiracism and 'environmentalism'.)
As I wrote a while ago; in natural Man, sexuality seems to be the second-most powerful motivator. Second, because Religion is - historically, and properly, the primary human motivator.
But in a post-religious society, such as we inhabit; this means that sex tends to become the strongest motivator for many or most people.
I think we can observe that this is broadly true, and that sex-as-motivator has been for many decades strongly encouraged, indeed enforced, by the major social institutions and corporations, mass media and the arts.
Such sexualizing of culture is a self-reinforcing positive feedback cycle; since many of the majority of secular people (including many of those who affect to be religious and identify as-such, but who in practice always put religion in a subordinate place to dominant - therefore Leftist - social mores) are already primarily motivated by something-to-do-with sex - and the encouragement of a sexual focus has the effect of continually adding petrol onto smouldering ashes, and then permanently fanning the resultant flames.
Even the reluctant and media-avoidant are unavoidably assailed by sexual stimuli and propaganda from all sides, on a daily (hourly) basis; which they cannot really ignore. This is why sex/ sexuality is nowadays primarily a motivator rather than something that someone does.
In other words, the overwhelming importance of sex in modern life is its role in thought; in imagination and day-dreams and (mostly) in personal and secret 'fantasies' - which are seldom 'successfully' enacted yet still exert a powerful, albeit mostly negative, effect on people's actual lives and decisions.
The modern sex/uality that so dominates modern societies is Sex In The Head - and may have little or nothing to do with the body; although such themes may (whether directly or indirectly) occupy a good deal of social interaction.
Yet, of its nature, personal motivations to do with sex are unsuitable as a basis for changing social arrangements - therefore sex/ sexuality first needed to be assimilated into a Leftist ideology; directed at society-as-a-whole.
This ideological assimilation of sex was accomplished from the 1960s (initially as 'free love' with easy divorce, then feminism, then campaigns to support various forms of unnatural sex/ sexuality, now the transagenda); by an army of ideologists, journalists, writers and artists, social scientists, critics, and bureaucrats.
These sexual commissars were (apparently) mostly personally core-motivated by sexuality, and they were supported (materially and by attention and encouragement) via multiple channels - commercial, official, and overtly political; presumably by those who were similarly motivated.
Thus, in a post-religious society; we have experienced a continual increase in concern with sex and sexuality; an increase which feeds upon itself - and is especially targeted on adolescents (and the increasing numbers of perpetual-adolescents) who, for biological reasons, are usually spontaneously focused upon sex and sexuality.
Sex has therefore proved to be the single most effective battering ram used against the residue of religion; almost certainly responsible for most of the epidemic of apostasy that has over the past several generations afflicted and destroyed first The West, then The World.
This means that - in a society increasingly dominated by Leftism - sex and sexuality are mainly pursued via ideology; and that people are strongly motivated by sexual ideology since (in absence of serious religion) sex represents their most powerful motivator - and they have been convinced that the attainment of their major life-motivations must run through support for Leftism.
Thus the sexual revolution has been one of the most important Litmus Test issues, determining whether someone is pro-The System, or pro-God (which are, increasingly, the only possible choices).
To understand this - and why it is that sex is such an important human motivator - yet properly not the most important motivator - is now a vital spiritual task for most people; and a task for which there is no help (but much hindrance) from the mainstream and mass media, and not much help from the mainstream of traditional churches.
As usual - this is a task that needs doing for (almost) every person; but external sources are corrupted; therefore we must take personal responsibility and do-it-for-ourselves and from-our-selves - which is possible, with guidance of the Holy Ghost.
Note added: It strikes me that I have relied on readers to join the dots here. Current news in the USA is about who gets to impose their sexual values on everybody else; and - in the context of our post-religious, hence sexually-motivated society - this is a set-up by The Establishment/ The System - intending further to undermine, scapegoat and destroy the residue of faithful Christians. But especially (as we perceive from evil-Leftist words and actions) the faithful in the Roman Catholic Church. Non-Catholic Christians should take note that the demonic powers (and despite the horrific extent of RCC corruption) nonetheless regard the Roman Church as a significant obstacle to their goals, worthy of specific attention. This I take as confirmation (for those who doubted) that there yet remains a significant and specifically-Christian force-for-Good in the RCC, as is.
Further note: As so often in these End Times; if the current situation is looked-upon as a learning opportunity - provided by God in context of the world as people have chosen; it provides a yet further, yet clearer example of the purposive and strategic evil of the global ruling Establishment and The System they control.