Gnosis is a theological and philosophical teaching, based on the esoteric tradition of eastern orthodoxy. Gnosis is not about gnosticism, it is a form of esoteric Christianity --work with the goal of self-realization, i.e. realizing one's identity with the creator. Many Indians identified with this as "your own true self dwells in the hearts of all." This refers to the Self alone is real.
Books:
Gnosis by Boris Mouravieff (volume I, II, & III), published by Agora Books for Praxis Institute Press (vol. I ISBN = 1-872292-10-0).