Just take a look at the Wikipedia article you linked to.
In it there are versions by: Huxley, Philo of Alexandria, Ficino and Pico della Mirandola, Agostino Steuco, Emerson, Blavatsky, Huston Smith, and a bunch of others.
Take a closer look at what these people believed and you'll see they believed different things (except that, again, they believed that there was a common source or experience that different religions stemmed from or were getting at).
For example, from the article, "the Egyptian god Osiris and the Greek god Dionysus had been equated as Osiris-Dionysus by the historian Herodotus as early as the 5th century BC", while "The mystic Ramakrishna's spiritual ecstasies included experiencing the sameness of Christ, Mohammed and his own Hindu deity". Not really the same, is it?
"Marsilio Ficino (1433–1499) believed that Hermes Trismegistos, the supposed author of the Corpus Hermeticum, was a contemporary of Mozes and the teacher of Pythagoras, and the source of both Greek and Jewish-Christian thought."
Again, not the same as the other two.
"Ficino saw his thought as part of a long development of philosophical truth, of ancient pre-Platonic philosophers (including Zoroaster, Hermes Trismegistus, Orpheus, Aglaophemus and Pythagoras) who reached their peak in Plato."
So now the peak is supposedly Plato, not Osirus, Christ, Mohammed, or a Hindu diety.
Then there's Steuco who believed "that philosophy works in harmony with religion and should lead to knowledge of God", but that's different from Emerson, who thought "an individual's intuition of truth was taken as the criterion for truth".
Etc, etc, etc...
By the way, in none of the above (or anywhere else in this Wikipedia article) is there any mention of what you said perennial philosophy (and, according to you, PKD) were getting at: that "there is only one moment". Where did you get that?
Perhaps a better umbrella for what I am referring to would be non-dualism.
i’m referring to Buddhism, Sufism, Hinduism, and Esoteric Christianity.
key figures would then be Patanjali, Buddha, Ramana Maharshi, Jesus Christ (Gospel of Thomas), St. Theresa of Avila, The Desert Fathers especially Anthony The Great, Shankaracharya, Rumi, and Hafez.
Patanjali in the non-dual Hindu tradition.
Buddha in the Buddhist tradition.
Jesus (as expressed in the Gospel of Thomas) representing Christianity.
Shankaracharya for advaita vedanta.
Ramana for Self-Enquiry.
Rumi, Hafez for Sufism.
also Somananda for Kashmir Shaivism.
Apologies if there was confusion in terms. It seems we were coming at it from different angles.
