For the briefest overview:

• Thelema, A.:A.: and the OTO are not inherently “Satanic” in nature
• Thelema (from the Greek θέλημα, meaning ‘will’) is a philosophy of intensely individual self-discovery, self-transformation and self-expression, based on disentangling oneself from social/cultural dogma, finding out who One really Is, and igniting oneself as a Star, in ever-perfecting expression of this. The principal source text of Thelema is The Book of The Law, transcribed by Aleister Crowley.
• A.:A.: is a teaching organisation, structured around one-to-one apprentice-style teaching and mentoring relationships. Their teaching, with “The methods of science, and the aim of religion“) encourages individuals in the pursuit of Thelema, helping them to overcome their inner and outer restrictions, and Become and express who They Really Are.
• Ordo Templi Orientis, more often known by the letters OTO, has ancient roots in Freemasonry, but now operates as a high-profile fraternal organisation, open to adult men and women. Like A.:A.:, the OTO is grounded in the Law of Thelema. However, the OTO is a much more public organisation, based around three lines of effort:
  1. Initiations (scripted dramatic experiences providing esoteric wisdom and facilitating personal empowerment and awakening), 
  2. Public performance of the Gnostic Catholic (EGC) Mass, a sacred and life-affirming ritual based on powerful and enlightening principles of Sex Magick, and
  3. Social connection, via scheduled events and networks of contacts, for thelema-friendly interactions  among like-minded people

These organisations, and Aleister Crowley, may sometimes be mentioned within the various Satanic communities, and in broader discussions around Satanism and the Left Hand Path in general.

However, it must be made blatantly clear that neither A.:A.: nor OTO (and neither did Aleister Crowley) identify in any way as “Satanic” even though there are some key areas where their interests overlap with those of the broader interests of Satanism in general.

Within these organisations, you may find some who explicitly identify as “Satanist”. But you will also find people who identify as Buddhists, Moslems, Christians, atheists, agnostics and so forth. Such is the inclusiveness and diversity of both the A.:A.:and the OTO, and the areas where they overlap, especially in aspects such as:

• Encouragement of critical thinking
• Rejection of dogma
• Valuation of development  of Self, even if it does not comply with social, cultural or family norms
• Respect for both themselves, and others, as emerging sovereign beings

To drive the point more strongly —  these organisations, and Aleister Crowley, are not “Satanist”; to identify them as such is an act of profound self-humiliation, revealing great ignorance.

So what are OTO and A.:A.:? And who was Aleister Crowley?

OTO is a fraternal initiatory organisation, originating in Germany in the 19th century, with deep roots in Freemasonry. However, with its discovery of, and practices around, a “Great Secret”, it became a form of irregular Freemasonry, with some similarity of aims and rituals, but with massive and growing differences.

OTO would likely have remained in obscurity, were it not for a certain (in)famous British Occultist, Aleister Crowley, accidentally stumbling on the OTO’s “Great Secret”, and inadvertently publishing that Secret in one of his magickal textbooks, without even realising he’d done so.

Aleister Crowley was one of a few dozen people identified by The Beatles as sources of major cultural influence — to the point where his photo features on the back of their landmark Sergeant Peppers Lonely Hearts Club Band album.

If there is just one phrase that best identifies him, it would be Do what thou wilt shall be the whole of the Law, a verse from The Book Of The Law, which he transcribed in 1903 in Cairo from an “otherworldly” intelligence named Aiwass.

This phrase does not mean “Do what you want”! Quite the opposite. It urges one to discover one’s own True Will, and to live a life of integrity, expressing their Will meaningfully through their life’s travels.

The Book Of The Law is revered by both A.:A.: and OTO as their single most sacred text. Its writings vary between audacious defiance, invigorating affirmations of individual sovereignty, subtle wisdom, common sense, esoteric references, and baffling obscure verses.

It can be argued that socially transformational movements such as the Beatniks, their later guise as Hippies, the “Me Generation” teachers of the 1970s to 1990s, all find their deepest sources of motive power originating from the teachings in that Book.

Another major foundation of these channels is the study of esoteric Hebrew QBLH (Qabalah, or Kabbalah), which seeks to unify all aspects of existence, and their inter-connections and mutual influences, in an integrated visual map of esoteric symbolism called the Tree of Life.

To sum up, Thelema is one of many currents of philosophy and spirituality which have some inter-mingling and shared aims with contemporary (non-Biblical) Satanism, but which define themselves separately from it.

Encompassing organisations such as the secretive lineage-based magickal teaching organisation A.:A.:, the public-facing fraternal initiatory body Ordo Templi Orientis (OTO), and the sex-magick inspired Gnostic Catholic Church, Thelema urges individuals to throw off the shackles of mass indoctrination, to discover their deepest unique essence, and fearlessly become and express who they really are.

Thelema argues that if everyone does their own Will, and abstains from interfering in the Will of others, society will transform into a harmonious constellation in which “Every man and every woman is a Star”.