What is Thelema?
The following is quoted from the OTO U.S. Grand Lodge Website
The religion known as Thelema was founded in 1904 by the English poet and mystic Aleister Crowley (1875 - 1947), who is regarded as its prophet. Those who follow the path of Thelema are called Thelemites. Thelema emphasizes individualism, and the uniqueness of each person's Will. As a result, it is very difficult to make blanket statements about its nature or (still more so) the natures of its adherents. Even the label "religion" fits Thelema awkwardly in some contexts - it is in other senses a philosophy and a way of life, while also overlapping with the set of practices and symbols commonly called "Magick".
Theology
The following notes on Thelemic theology are based primarily on the writings of Aleister Crowley. These notes are not intended as interpretation or commentary on The Book of the Law outside the bounds of the Prophet’s writings, nor do they represent a definitive statement of Thelemic belief.
The theology of Thelema postulates all manifested existence arising from the interaction of two cosmic principles: the infinitely extended, all-pervading Space-Time Continuum; and the atomic, individually expressed Principle of Life and Wisdom. The interplay of these Principles gives rise to the Principle of Consciousness which governs existence. In the Book of the Law, the divine Principles are personified by a trinity of ancient Egyptian Divinities: Nuit, the Goddess of Infinite Space; Hadit, the Winged Serpent of Light; and Ra-Hoor-Khuit (Horus), the Solar, Hawk-Headed Lord of the Cosmos.
Customs
Nearly all Thelemites keep a record of their personal practices, and their progress therein, in a “Magical Diary”. Most Thelemites also practice a particular form of prayer four times per day, which is specified in a work called Liber Resh vel Helios. This work is included in Book 4, which is available through our online bookstore. Thelemites often take mystic names or “magical mottoes” for themselves as a sign of commitment; and customarily greet each other with the phrase, “Do what thou wilt shall be the whole of the Law”; to which the customary response is, “Love is the law, love under will”. Sometimes these phrases are abbreviated by the simple statement of the number “ninety-three”, which number signifies both “Will” and “Love” through a particular form of numerology of significance within Thelema. Read more here...