...IMO, that becomes more fundamentalist in nature as one moves further left.

That's why we see the performative virtue-signalling, censorship of alleged blasphemy running counter to state-church orthodoxy, mass belief in myths, unflinching faith in the righteousness of the cause (and in the inherent sin inside anyone who disagrees), the drive to cast out non-believers from society and the compulsion to judge and micromanage every nook and cranny of life -- however trivial -- according to their political catechism.

While liberalism can present like a mental disorder, it's really just a manifestation of the human need to believe in and belong to something greater than oneself, even if one must opportunistically suspend disbelief and rationality to do so.

Relative to traditional religion, however, instead of that "something greater" being God or some other supernatural power, liberals worship the omnipotence and omniscience of government "experts", which, whether by design or accident, sometimes just boils down to worshipping themselves.