(Sanksrit, literally "Diamond Vehicle") Also known as Tantrayana and Mantrayana. A tradition of esoteric Buddhism. 

"It is evident that the Vajrayana Path is really profoundly Buddhist and Christic... The Vajrayana school, with its deep esotericism, leads us along the sexual path to the incarnation of the Word and final liberation... Disciples of the Vajrayana school labor tenaciously in the “Forge of the Cyclops” (sex) with the intelligent objective of achieving Innermost realization of the Illuminating Emptiness." - Samael Aun Weor, The Mystery of the Golden Blossom