Thelema is also the name of a philosophical/religious system founded by Aleister Crowley in 1904. The central doctrine of this system is that knowing and doing one's True Will is the ultimate purpose and duty of every being. Crowley's 'received' text Liber AL vel Legis or The Book of the Law is the central document which provides the basis for Thelema. This book declares that "Love is the law, love under will", "Do what thou wilt shall be the whole of the Law", and "The word of the Law is Thelema".
The Greek Thelema is the basis of the word Thelemite, coined by Francois Rabelais, the 16th century French humorist-philosopher in his classic work Gargantua, where it is used to describe the dwellers in a sort of anti-monastery, the Abbey of Thélème. The word Thelemite appears in The Book of the Law, and is used self-referentially by the adherents of Thelema.
Compare with: Wiccan Rede