Before we understand whether ISKCON is sectarian or not, I would like to first present to you one of the fundamental teachings which Lord Krishna taught to Arjuna. In Bhagavad Gita Chapter 2, Text 13, this is what Lord Krishna teaches Arjuna:
As the embodied soul continuously passes, in this body, from boyhood to youth to old age, the soul similarly passes into another body at death. A self-realized soul is not bewildered by such a change.
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This statement essentially means that we are not these bodies but spirit souls. In other words, when I say “I” or “You”, I do not mean to refer to my body or your body. The living entities, I and You, are not the bodies which we can see with our naked eyes. We are something different from these bodies, transcendental to gross matter. Since we are not these bodies, any identification that we accept based on this body is false in the absolute sense.
For example, right now I call myself Indian because my body was born on Indian soil; I was born to Hindu parents and therefore I also identify myself as Hindu. If I were born to Christian parents in a land, say the US, then I would call myself a US Christian. Although the same “I” is under consideration in both cases, the identification that I accept is different in both cases, BECAUSE I AM THINKING THAT I AM THIS BODY THAT I POSSESS, which I am not actually. This is similar to saying I am a Red person if I wear a red shirt or I am a blue person if I wear a blue shirt. Although I am not the shirt I am wearing but different from the shirt, I am under the misconception that I am this shirt and hence identifying myself with its color.
So to summarize the above teaching we can make the following statement:
I am a spirit soul, part and parcel of the Supreme Lord, encased within this material body. It is wrong to think that I am this body and there is a soul within this body.
Srila Prabhupada, the foundar acarya of ISKCON, explains that Hindu, Muslim, Christian, Indian, American, White, Black – these are all rubber stamps that puts the living entity into the illusion that he is this body. Thus, a true non-sectarian approach can be applied only if we do not consider any bodily designations. An organization which has this kind of approach towards the living beings can be truly termed as spiritual because the living entities are originally pure spirit souls, part and parcels of the Supreme Personality of Godhead and untainted with any material designations.
In ISKCON temples and programs, we find that people from all religions, castes, creeds, races and nationalities come together and glorify the Supreme Lord. They have the proper understanding that all these designations which applies to the external body is not the actual identity of the soul. Since we are part and parcels of GOD, we are actually brothers and God is our Supreme Father. Because bodily discriminations are set aside, there exists true love and harmony amongst the devotees. Therefore ISKCON is truly a non-sectarian organization.
Regarding monotheism, it is true that ISKCON propagates the philosophy of one GOD. GOD is the Supreme Person and He has many transcendental qualities. Based on His qualities and activities, He is addressed by different Names. All these Names are identical to the Personality of Godhead because He is Absolute.
As you have correctly observed, the teachings of ISKCON and Christianity mirror each other in several ways. Jesus Christ was an empowered representative of GOD and came to this world to spread GOD consciousness. Similarly, Prophet Mohammed was another empowered representative who performed a similar wonder. The sad part, however, is that none of their followers are truly following the teachings laid down by them. They misinterpreted the original teachings and concocted so many additional philosophies to such an extent that the original purity is almost lost. In the name of economic and scientific development, the modern day human society is now actually progressing towards utter devastation.
In order to save the human society from degradation, in the year 1486, the Supreme Lord Himself in the form of Lord Chaitanya came and gave the original pure teachings of God consciousness. He propagated the chanting of the Holy Names of GOD as the only form of self-realization that is possible in this Kali Yuga, the age of quarrel and hypocrisy. Following in the footsteps of Lord Chaitanya, His Divine Grace A. C. Bhaktivedanta Svami Prabhupada established the International Society for Krishna Consciousness in the year 1965 in order to spread these divine teachings.
My humble request to you is that please try chanting the names of GOD. You will certainly perceive the difference in due course of time. There are no hard and fast rules as to what names should be chanted. However, it is recommended in the Vedic literatures that the 16-worded Hare Krishna Mahamantra is the most suitable mantra for this day and age. As you might already know, the mantra is:
HARE KRISHNA HARE KRISHNA KRISHNA KRISHNA HARE HARE |
HARE RAMA HARE RAMA RAMA RAMA HARE HARE ||
If you have any prejudice against chanting HARE KRISHNA, then you may chant the names of Christ. But please do chant. Hare Krishna.