http://en.wikipedia.org/wiki/Gnosis#Greek_Orthodox
Gnosis in Greek Orthodox thought is the spiritual knowledge of a saint (one who has obtained theosis)[26] or mystically enlightened human being. Within the cultures of the term's provenance (Byzantine and Hellenic) Gnosis was a knowledge or insight into the infinite, divine and uncreated in all and above all,[27] rather than knowledge strictly into the finite, natural or material world.[28] Gnosis is a transcendental as well as mature understanding.[29] It indicates direct spiritual experiential knowledge[30] and intuitive knowledge, mystic rather than that from rational or reasoned thinking. Gnosis itself is obtained through understanding at which one can arrive via inner experience or contemplation such as an internal epiphany of intuition and external epiphany such as the Theophany.

In the Eastern Orthodox Philokalia it was emphasized that such knowledge is not secret knowledge but rather a maturing, transcendent form of knowledge derived from contemplation (theoria resulting from practice of hesychasm), since knowledge cannot truly be derived from knowledge but rather knowledge can only be derived from theoria (to witness, see (vision) or experience).[31] Knowledge thus plays an important role in relation to theosis (deification/personal relationship with God) and theoria (revelation of the divine, vision of God).[32] Gnosis, as the proper use of the noetic faculty plays an important role in Eastern Orthodox theology. Its importance in the economy of salvation is discussed periodically in the Philokalia where as direct, personal knowledge of God (noesis; see also Noema) it is distinguished from ordinary epistemological knowledge (episteme—i.e., speculative philosophy).