Modern demonic possession is qualitatively different from that of the past. For a start it is a mass phenomenon, and enormously more common than in any previous era. And secondly possession nowadays is much less personal, far more abstract, then before...
So much so; that "Ahrimanic-demonic possession" is taken-for-granted as the attribute of a good employee, an obedient citizen; a nice and decent person with all the right opinions.
Traditional demonic possession was an individual phenomenon. In return for greater power and/or lustful pleasure; the host sets aside his own ego and allows a demonic spirit to inhabit the space.
In terms of responsibility; an individual refuses to take responsibility for his own choices - and hands-over his will to the demon.
The consequence is that proud, often brave; spectacularly selfish, violent, sadistic and individualistic evil of the past; which I have termed Luciferic.
Mass modern evil is very different; and anything-but spectacular: it is the grey evil of grey Men.
Modern evil is detached, impersonal, cold, grey - bureaucratic. This is Ahrimanic evil. Instead of being short-termist and self-indulgent; Ahrimanic evil is characterized by pathological pseudo-altruism, self-hatred, and a suicidal despair.
Ahrimanic possession is driven by a self that refuses to be a self; an 'ego' that refuses to take responsibility for its own freedom; and instead hands-over ultimate authority to 'the system' - that is to an abstract 'group mind' which functions by impersonal procedures and processes (such as committees and votes).
In different words; the individual-ego submits to a group-ego*; and the negated individual passively-absorbs values from the group-ego.
Or; Ahrimanic possession is a consequence of deliberate surrender of Being, a result of regarding oneself as an acted-upon thing, rather than an intrinsically free Being.
Mass modern Ahrimanic demonic possession (which is so common as to be statistically-normal in the West: it is indeed the New Normal) can therefore be conceptualized as a form of group-possession.
Ahrimanic possession is when the group-ego is colonized by demons - and the individual ego merely submits to that group ego.
So, mass modern demonic influence is at one remove and indirect; its motives abstract and procedural; which is probably why the vast and pervasive extent of modern demonic possession is so seldom recognized, so easily denied.
* For more on the group ego, see this post.