The comment you made in Darius Kadivar’s blog is verbatim what the Neo-Traditionalist school of Rene Guenon, Ananda K. Coomaraswamy, Frithjof Schuon, Seyyed Hossein Nasr, Julius Evola and company (including myself) call the Primordial Tradition. We say that all of the established Traditions are so many fragmentary facets of a Primordial Tradition functional at the beginning of this present great kosmic cycle of time, i.e. the Golden Age before the present fall or what the Mazdaean texts indicate as the pre-diluvian world before the invasion of the counterpowers of darkness. Another way of saying Primordial Tradition is the Perennial Philosophy or Eternal Wisdom (sophia perennis). Shihabuddin Yahya Sohravardi, shaykh’ul-ishraq, likewise speaks of it as the Javidan-Khirad. He says the Prophet-Imams and establishers of this Primordial Wisdom Tradition are Agathodaemon, Hermes Trismegistus, the mythic Persian kings Kay-Khosrow and Jamshid, and Asha Zarathushtra. He also says that the Master of this Wisdom Tradition, who derived his own transmission from Pythagoras, Empedocles, Parmenides and the Egyptian priests, is none other than Plato! Plato, in turn, paid homage to Zarathushtra in several of the Letters.
What you call sweetness in this trajectory is what we call esotericism/gnosis (‘irfan/ma’arifa). The bitterness, or poison pills as I call them, is exotericism (mazhab-gara’i). Zoroastrianism, or the original pre-Sassanian Mazdaeanism, did not even distinguish this dichotomy, since their notion of religion as such, i.e. the Mazda Yasna, was Daena. This, incidentally, is a highly autochthonous and shamanic notion of what spirituality is. Now Daena as din is the Hebrew-Arameo-Syriac and Arabic lone word from Gathic Avestan meaning “religion.” In Gathic Avestan Daena has a multifaceted meaning, denoting simultaneously ‘revelation‘, ‘religion‘, ‘conscience‘ and, most importantly, ‘Angel‘ or Yazata (titulary divinity).
Daena is Zarathushtra’s Angel of Revelation (analogous to Gabriel in Islam to Muhammad), but it is also the soul’s Perfect Nature or syzygy (two-in-one). Symbolically Daena in the Gathic texts is characterized as being female, i.e. the Eternal Woman in all-things. Note the idea of the Shekinah (the feminine presence of YHVH in Judaism) and the notion of the Sophia in Gnosticism. Daena is also that being that appears in the post-mortem state leading the soul of the righteous across the razor-sharp Cinvat Bridge to either eternal felicity (if successfully crossed) or to its opposite into damnation within the realm of Ahriman and the counterpowers of darkness (if failed). Every person is individually responsible over a lifetime for developing their own correct relationship with their Daena. The Avestan texts say that in the post-mortem state the righteous shall behold their Daena as either a demon, according to the negative actions (or karma) of their physical lives, or an Angel of Light. In other words, the visage the soul beholds of its Daena in the post-mortem state is completely up to each soul to bring to fruition, and this in itself determines whether the soul will cross the Cinvat Bridge over to the other side into Eternal Light or into eternal darkness.
Amongst his Platonic Neo-Zoroastrian compilation of prayers known as the Book of Hours, and composed in Arabic, the aforementioned Shihabuddin Sohravardi, shaykh’ul-ishraq, offers a beautiful prayer he composed to the Perfect Nature, i.e. Daena. To him, as to the ancient Mazdaeans, this prayer epitomizes the true meaning of religion/din/Daena, as true religion is here seen as the individuated relationship each soul develops with its own Holy Guardian Angel, i.e. its Perfect Nature/syzygy/Daena. I share my English translation of it here below (and also would recommend a reading of the first tractate from the Corpus Hermeticum entitled the Poimandres as a comparison in ideas):
SOHRAVARDI’S HYMN TO THE PERFECT NATURE
O Thou, my Lord and Prince, most Holy Angel, my most precious and beloved spiritual being! Thou art my Father and my Mother, the Sun and the Moon, who gave birth to me in the world of the Pure Spirit, and Thou art my child and sibling in the world of my thought! With divine permission Thou art entirely dedicated to the government of my person! Thou art the one whose fervor intercedes for me before the Godhead, the God of all Gods, to make up for my deficiencies! O Thou who art clothed in the utmost radiance of the divine Lights! O Thou who resides at the summit of the degrees of perfection, I implore Thee, through the One who has overwhelmed Thee with such sublime nobility, who hath bestowed upon Thee such an immense effusion of grace! O precious one, may Thou manifest Thyself to me at the hour of the Supreme Epiphany! May Thou showest me Thy resplendent Face! May Thou be my mediator before the God of Gods in the effusion of the Siniatic Light of mystical Secrets! May Thou lift the veils of darkness from my heart! This I pray in the name of the One who hath claim over Thee and ranks over Thee! I call upon Thee, O Powers and sublime spiritual Angels, O Ye who art the wisdom of the sages, the sagacity of the seers and the knowledge of the wise! Hearken unto me and appear before me and bring me near to Thy magisterium! Guide me with Thy wisdom and protect me with Thy powers! Make me understand what I do not understand, realize what I do not realize and see what I do not see! Turn me away from the dangers that lurk in the ignorance, the forgetfulness and the hardness of my heart, in order to have me attain to the ranks of the ancient sages and inspired prophets, in whose hearts wisdom, insight, vigilance, discernment and comprehension made their permanent indwelling! May Thou also live forever in the innermost recesses of my heart, and never ever separate Thyself from me! Amen. (my translation)