Within orthodox Hinduism, ISKCON is often considered to have little or no legitimate connection to traditional Hinduism because it is a modern interpretation of a specific focus within Hinduism. Many elements of the traditional faith are removed. For example, ISKCON bases its teachings on those of Bhaktisiddhanta, rejected caste as a matter of birth, and taught that it was the state of one's heart that counted. This ultimately means that ISKCON unlike traditional Hinduism, allows anyone to enter the Brahmin caste. Traditional Hindus would not initiate non-Brahmins into the Brahmin caste. Another departure from traditional Hinduism is that the ISKCON movement regards the Bhagavad Gita as central to its teachings; however, for traditional Hindus this is not regarded as highly as is not a shruti text (that which is heard – directly from God) and is just a remembered smriti text. Moreover, ISKCON members follow the Bhagavad Gita as translated and commented on by A.C. Bhaktivedanta Swami Prabhupada, which has its own particular interpretation that may contradict the views of traditional Hinduism. For example, ISKCON devotees see the Gita as being an open text which can be interpreted in many ways e.g. the story of the battlefield is allegorical – the field representing the human conscience, Arjuna representing humankind and Krishna being the charioteer who steered him in the right direction. The more traditional interpretation of the Gita within Hinduism is that the story is more literal and is proof that people should fight in a just war. The allegorical interpretation obviously appealed more to a peaceful approach to conflict and so was popular with the hippie culture.
Related to this, the missionary aspect of ISKON in its attempts to actively convert non-Hindus is not an important feature of traditional Hinduism. Kim Knott (A Short Introduction to Hinduism, OUP, 2000), states that ISCON promoted ‘Public worship, processions, and pilgrimages take the name and form of Krishna on to the streets of India's villages and the cities of the West and beyond’. Traditional Hinduism, which sees non-Hindus as being outside the caste system does not share ISKCON's drive to share their beliefs with others.
Finally, ISKCON venerates Krishna as the supreme being, the ultimate truth; this is not regarded by some as a legitimate form of Hinduism because in Hinduism, Krishna is seen as the 8th avatar of Vishnu and therefore Vishnu would be given higher status.
However, it can also be argued that ISKCON is a legitimate form of Hinduism. Ian Jamison (Hinduism, Philip Allan, 2006) does take a different line of argument when he states that that ISKCON ‘is now largely considered not as a new religious movement, but as an authoritative part of Hinduism.’ He argues that it still shares the same core beliefs such as karma, moksha and the transmigration of the soul and so has not totally separated itself from its traditional roots.
In addition, devotes of ISKCON tend to follow traditional Hindu practices regarding ritual purity before worship for example, shaving their heads (although with a slight variation regarding the shikha). Moreover, the ISKCON movement also follows the style of worship set out in the vedas e.g. singing hymns and the congregational chanting of Hare Krishna mantra.
It could be argued that bhakti yoga is central to wider Hinduism: as Krishna states in the Bhagavad Gita Chapter 9 v26 (to the warrior Arjuna) ‘If one offers Me with love and devotion a leaf, a flower, fruit a water, I will accept it.’ Just as in traditional Hinduism, ISKCON follows the devotional aspect of bhakti worship in a temple (mandir).
In conclusion, it appears that whilst ISKCON shares many of the characteristics of Hinduism, such as forms of worship and some core beliefs, in other ways it appears to be a distinctive departure from traditional Hinduism, especially in views about the role and understanding of the Bhagavad Gita and the prominence given to Krishna. Overall, it may be the case that for some within the Hindu faith ISKCON should be considered to be a separate religion rather than a legitimate movement within Hinduism; however, one wonders whether or not those who are outside the Hindu faith would see any significant difference in the face of the diversity of beliefs and practices within Hinduism itself.