ISKCON (International Society of Krishna Consciousness) is a major world institution dedicated to the worship of Sri Krishna. They venerate Sri Chaitanya who is said to have had a direct experience of Sri Krishna in the 15th Century (http://en.wikipedia.org/wiki/Chaitanya_Mahaprabhu). Whatever experience he had and whether that experience makes him an avatar of Sri Krishna, if we worship Sri Chaitanya Mahabprabhu as if he was Sri Krishna, we will be worshipping Sri Krishna, but if we worship Sri Chaitanya as himself, we will not be worshipping Sri Krishna. ISKCON should note that: (a) there are no mantras to attain or invoke Sri Krishna; (b) Rama has nothing to do with Sri Krishna so that the supposed mahamantra ‘Hare Krishna, Hare Krishna, Krishna Krishna Hare Hare, Hare Rama, Hare Rama, Rama Rama Hare Hare’ has no effect – Rama is a different type of God to Sri Krishna; and (c) Sri Krishna is only realised through gyan yoga performed through total devotion to truth.
In the Gita Sri Kishna says ”I am the OM in all vedic mantras” so ratikala in Religious Forums argued that all mantras invoke Sri Krishna including the Mahamantra of nama japa, therefore it is not through gyan yoga that one realises the supreme but through devotion alone. She added that gyan yoga without bhakti is merely dry speculation if one were to realise the lord through gyan yoga then one would spontaneously be filed with love and chant nama japa in the mood of pure bhakti. My response to that is that the meaning of OM is ‘truth’ so that bhakti is to truth which is Sri Krishna.
The other point with which I digress from ISKON is their theology of representing a goddess presumably in Srimati Radarani as the eternal consort of Lord Krishna. Thus they consider Meera bai (http://en.wikipedia.org/wiki/Meera) to have been an avatar of Radharani not of Sri Krishna. To my knowledge, Sri Krishna does not have an eternal consort.