Spiritual development appears to be divided into two-paths, which have opposed and conflicted with each other from what appears to be the beginning of organized religion. The two paths are often separated as the puritanical right hand path consisting of most organized religions where a deity(ies) is(are) propagated as saviors from what is often deemed to be the dirty occult (hidden) left hand path. Even in the mystical we still have that separation as evidenced by the Qabalist Tree of Life where one seeks to know, as opposed to the Qabalist Qliphoth where one seeks to become. Nonetheless, the left hand has been historically used to cleanse oneself, and is thus considered filthy, like Tantra which seeks to unite a Yogi into cosmic self realization as the main goal, as opposed to propagating a deity.
Nonetheless, the two aspects have often been at war with each other, where the left hand path is often considered "evil", where organized exoteric religion has historically sought to exterminate those of the left establishing secret societies. Though, it is my belief that the higher ups in organized religion practice left hand path, but expound right hand path in order to create submissiveness, such can be found through the numerous symbols used in Catholicism, the root of the majority forms of Christianity (not Gnosticsm, where the Cathars were eliminated to make way for Mithraic Romanism...ahem Catholicism via creed of Nicea). Numerous symbolism of the subtle body can be found within Catholicism, though the masses are still clueless, and/or call it the "illuminati".
The left hand path has always been a home for those persecuted by the higher ups, like the Tantric tradition from exoteric Brahmanic rule, Gnosticism/Knights Templars (the source of the Baphomet in correlation with the Hashashin/Order of the Assassins) and really a whole plethora forms of esoteric Christianity like the teachings of Swedenborg/William Blake from the majority forms of Christianity. Though, it took me decades to really discern the practices between the two aspects, and feel that both are necessary for proper development. However, that train of thought is eluded by those on the right hand as evidenced by the following parable often expounded by devotees.
As a common devotional parable goes, there was once a devotee and a yogi, who practiced their techniques with many years of earnestness to have a glimpse of the divine. Krishna appears to the yogi, where the yogi asks, "how many years before I am liberated"? Krishna responds with "you've done very well, you will only have three more life-times before liberation". However, the yogi wanted immediate liberation, where three more lifetimes was too much. The yogi gives up his practice in disdain and returns to common life. Krishna thereafter proceeds to the devotee where the devotee asks the same question, "how many years before I am liberated"? Krishna responds to the devotee, "though you have lovingly served me, you still have as many lifetimes as there are leaves on this tree". In excitement, the devotee thanks Krishna elated that he has many more lifetimes to worship his divine. Upon seeing that elation, Krishna immediately brings the devotee to Krishna's heaven.
Though the parable shows the strength of devotion, in my belief, such is required to open the heart chakra. Without such opening, one cannot advance into the higher realms, or even properly open the third eye, which would open the rainbow light body/merkaba. In addition, that's how you purge Karma and keep it off, by being unconditionally loving no matter the crucifying life circumstances to the point where you can energetically forgive and love everything. That might bring liberation on its own course, but another angle is the left hand path. Those on the left do not necessarily seek to just be with a divine of choice, if they have so chosen one, but they seek to be that which is divine, which still requires the opening of the heart. Even those working with lower entities, the way to subdue them is to love them, the way Lord Padmasambhava shifted the negative entities into becoming the protectors of Dharma.
As indicated above, the devotional right hand path seems to be a stepping stone the dangerous left hand path. I say dangerous as this is a path where one integrates the shadow self by facing one's inner demons (lower emotions), which can create dangerous inner vibrations that via law of attraction manifest in the external world requiring clearing. Having devotion, having guides, will make this process much less dangerous, which without such, can do a number on one's psyche. As indicated by the parable, it's the fast path route that can get you to spiritual completion, though a guide can also work wonders.
Nonetheless, it appears that the left hand path is the proper inclination for the next step of spiritual evolution, as the phases are laid out within the Advaita Vedantic text, the Tripura Rahasya (Secret of the Supreme Goddess). As stated, "One learns true devotion to God after a meritorious life continued in several births, and then worships Him for a long time with intense devotion. Dispassion for the pleasures of life arises in a devotee who gradually begins to long for knowledge of the truth and becomes absorbed in the search for it. He then finds his gracious Master and learns from him all about the transcendental state....The inner Self is realized in advanced contemplation and that state of realization is called nirvikalpa samadhi."
The right hand path is that of the dualist who seeks God outside of himself. Such consists of the majority of religions, and in Hinduism, is found under Dvaida Vedanta with the belief that the soul (atma) is separate from the ultimate reality (Brahman). When one longs for Truth beyond devotion, one seeks the left hand path of nonduality, recognizing the God within. Such consists of what esoteric traditions have sought to learn, and in Hinduism, is found under Advaita Vedanta with the belief that the soul (atma) and the ultimate reality (Brahman) are identical (like the air outside of a jar and within a jar, it's still air). Brahman, the ultimate reality is simply "Brah" or expansion, and "Mana" or mind. Hence, expansion of mind/consciousness/awareness.
Such individuals have faced persecution by those on the right hand, where it is blasphemous to be a God, to act like a God, to feel like a God, even provided that our ancient traditions told us who we really are. As Jesus said in John 10:34, "Jesus answered them, Is it not written in your law, I said, Ye are gods?". Acknowledging this power is not "evil" where all such beings should be grouped into an evil left hand "illuminati". What makes such power evil would be what is done with it.
Hence, it may be time to recognize that both hands belong to the same being. And that being is the only one in existence, the Cosmic Self.
Overly educated and continuously exploring and revealing more behind the veil.
"It cannot be too highly emphasized that the mystic swims in the same waters in which the psychotic drowns."
-James Wasserman, The Mystery Traditions