On the question of Perennialism/Universalism
Perennialism is true. But beyond doctrine, there are few in this mundane world of ours who can be said to have realized the contents of the metaphysical doctrines they espouse genuinely on that kind of universal level (that is not saying there aren't any; just asserting that the genuine ones are few and far between) - and this goes for all the existing traditions, as far as I am concerned. The Reality of universal Truth versus its mere articulation are often two completely different things. This age seems to be losing sight of this fine distinction where representation is erroneously taken as actuality. They are not, but the inverted spirit contaminated by the counter-spirit of capitalism no longer understands this fine line. I saw more corruption and abuse in Buddhist and Hindu orders established in the West than almost with anyone and anywhere else, esp. during the time I was living in New Mexico in close proximity to Santa Fe and Sedona, Arizona where there were many of these. What good is the Vedanta, the Tantra, Mahayana, Madhyamika or Vajrayana if its representatives become as cynical, corrupt and blind as any capitalist - and sometimes even worse (since a straitlaced capitalist is not pretending to be anything other than what they are) - when they sexually, emotionally, financially, spiritually and criminally abuse and/or prey off of gullible people who put their trust in such false, venal or corrupt gurus, lamas, rinpoches, Yoga masters and similar as these to guide their spiritual development?
This is a problem that the 20th and 21st centuries have repeatedly demonstrated and reinforced time and time again. This is also why I generally take the Guenonian Neo-Traditionalists as being largely full of sh*t when they pontificate on things like orthodoxy since out of their ranks arose a highly metaphysically articulate lecher and fiend such as Frithjof Schuon, whose corruption I wrote about in 2016 here, never mind an extremely articulate and intellectual powerhouse like Julius Evola (an unrepentant Fascist).
In my Book, the rejection of the insān kāmil is a rejection of God, the Ultimate Reality, etc. Take it however you want. The Muslims persecuted and rejected the Family of the Prophet (ع), the True Inheritors, and spent the next nearly 1200 years going from one deadly crisis to the next (with the Mongol onslaught coming near close to annihilating the Islamic world at one point in entirety). They then rejected the Primal Point and the Bayān, and during the past 174 years have experienced the 1200 years that preceded it in a compact, reinforced form on steroids. In my mind, there is a straight line from the rejection of the Point of the Bayān to crisis of the NAKBA, whether in 1948 or today. As I stated matters in the Bezel of the Wisdom of Pointhood in the Word of Ali Muhammad: God sent the people of Noah a physical deluge for rejecting Him; God has sent the people of the Furqān a spiritual deluge for rejecting their Qā'im and Mahdī in the Primal Point. Causes have effects, as it were, and usually those unseen causes not generally recognized can have the deeper and more devastating consequences and effects. Whatever the historicity of things, which the jury still remains out on, isn't this one of the key takeaways from what happened to the Jews based on how they treated Jesus Christ (ع)?
Is there even a question then as to why belief - or rather gnosis , i.e. ma'rifa - in the locus of a True Divine Manifestation is so important even when it may appear on some level to be exclusivist? Have the Qur'an or the Shi'i hadith corpora asserted any differently? I have found many contemporaries who talk about perennialism or try to assess a given creed based on how perennialist or universalist it may or may not be engaging in a sort of delusional game of optionalization qua a Wittgensteinian language game using religion to that end. This is the malevolent postmodern neoliberal zeitgeist in the domain of religion and spirituality in operation where most people are really shopping for a club with a doctrine to belong to and not to follow a Path to the All-High.
Unless one has direct Taste and experience of these Perennial and Universal Truths, assessing a creed based on such criteria on a mere intellectual level is like fallaciously assessing the validity of relationships based on whether they subscribe to polyamory or not (and, believe me, perennialism/universalism is being used by some people in a promiscuously intellectual sort of way sometimes). A genuine spiritual Path is like a marriage with all the rules normally around such well functioning relationships intact occurring within it, but on another level and plane. So realize the Truth first and then its perenniality/universality will show itself to you beyond just talk and words on a page - or mere consensus. This can be easily proven based on the phenomenology of love itself. One can be with many people, but it is always that one who becomes that One True Love of one's life one never ever forgets. This dynamic is both a telling metaphor for the God/human dynamic as well as the exclusive focus of a given Path to the All-High regarding itself (provided, that is, the Path is real and not one of the endless varieties of snake-oil we see in our times). But once you get There - and only when you get There - then you get to see, taste and feel the perenniality/universality of things in the God manifested in every form of belief. My point of departure on this specific question comes from Ibn 'Arabi’s famous statement made in the 2nd volume of the Futūḥāt al-Makkīyyah, and I work from there:
So glory be to the One Who manifests everything, for It is their very essence!