Hinduism is not a religion. It is a Weltanschauung or a worldview. One of the most crucial components of this Weltanschauung is the acceptance of all religions, sects or cults as true and valid. Swami Vivekananda (Complete Works, 3: 112-113) said: "In India the same competing gods had been struggling with each other for supremacy, but the great good fortune of this country and of the world was that there came out in the midst of the din and confusion a voice which declared, 'That which exists is One; sages call It by various names.' It is not that Shiva is superior to Vishnu, not that Vishnu is everything and Shiva is nothing, but it is the same one whom you call either Shiva, or Vishnu, or by a hundred other names. The names are different, but it is the same one. The whole history of India you may read in these few words. The whole history has been a repetition in massive language, with tremendous power, of that one central doctrine. It was repeated in the land till it had entered into the blood of the nation, till it began to tingle with every drop of blood that flowed in its veins, till it became one with the life, part and parcel of the material of which it was composed; and thus the land was transmuted into the most wonderful land of toleration, giving the right to welcome the various religions as well as all sects into the old mother-country.”
Hundreds of religions, sects, or cults accept the Hinduism Weltanschauung. They are sometimes referred to as the Hindu religions. These various religions were grouped into six clusters by Adi Shankaracharya, more than 1200 years ago: (1) Vaishnavism (Vishnu); (2) Shaivism (Shiva); (3) Shâktham (Shakthi); (4) Gânâpathyam (Ganesha); (5) Skândham/Kaumâram (Kârthikeya); (6) Sauryam (Sûrya).
It is not possible to get even a minimal understanding of Indian or Hindu religions without getting an idea of the theory of Ishta. According to Swami Vivekananda (Complete Works, 4: 51-57), “The theory of Ishta is a subject requiring careful attention because with a proper understanding of this, all the various religions of the world can be understood. The word Ishta is derived from the root Ish, to desire, choose. The ideal of all religions, all sects, is the same — the attaining of liberty and cessation of misery. All of us want to get rid of misery; we are struggling to attain to liberty — physical, mental, spiritual.
Though the goal is one and the same, there may be many ways to reach it, and these ways are determined by the peculiarities of our nature. One man's nature is emotional, another's intellectual, another's active, and so forth. Again, in the same nature there may be many subdivisions... Each one of us is born with a peculiarity of nature as the result of our past existence. There is a peculiar movement, a peculiar train, in each one of us; and therefore each one will have to find way for himself.
This way, this method, to which each of us is naturally adapted, is called the "chosen way". This is the theory of Ishta, and that way which is ours we call our own Ishta. Each one sees God according to his own nature; and this vision, conditioned by our own nature, is our Ishta. We must understand that truth seen from different standpoints can be truth, and yet not the same truth... We must remember that an absolute truth is only one, while relative truths are necessarily various. Take the sun. The sun is one; but when you and I and a hundred other people stand at different places and look at it, each one of us sees a different sun. So, in relative perception, truth always appears various. But the Absolute Truth is only one. Therefore we need not fight with others when we find they are telling something about religion which is not exactly according to our view of it. We ought to remember that both of us may be true, though apparently contradictory.
This theory of Ishta, therefore, means allowing a man to choose his own religion. One man should not force another to worship what he worships. For instance, when I am a child, my father puts a book into my hand which says God is such and such. What business has he to put that into my mind? How does he know what way I would develop? And being ignorant of my constitutional development, he wants to force his ideas on my brain, with the result that my growth is stunted.
We see then that a congregational religion can never be. The real work of religion must be one's own concern. I have an idea of my own, I must keep it sacred and secret, because I know that it need not be your idea. Secondly, why should I create a disturbance by wanting to tell everyone what my idea is? This Ishta should be kept secret, it is between you and God.
This is the theory of Ishta. It is the only way to make religion meet practically the necessities of different constitutions, to avoid quarrelling with others, and to make real practical progress in spiritual life... Why should I not speak of my Ishta to others? Because it is my own most holy thing. It may help others, but how do I know that it will not rather hurt them?”
A correct understanding of the theory of Ishta leads to three significant outcomes:
1. The theory of Ishta allows for infinite customization. One can worship the child Krishna, while another can worship the charioteer Krishna. The Krishna worshipped today may evolve into a different Krishna tomorrow. So, religion is dynamic. It also allows for adding another God, without throwing away the earlier God.
2. The Ishta is a very private entity. Often, even the husband may not know what the Ishta or religion of the wife is. It would be the height of ignorance to ask people to specify their religion or Ishta, for any reason whatsoever.
3. Moreover, religion is not hereditary. A father following Shaivism religion does not necessarily mean that his daughter is also following Shaivism religion. How can you call the daughter of a Shiva-worshipper (Shaivite) as a Shiva-worshipper, if she does not worship Shiva?
Swami Vivekananda (Complete Works, 2: 364-374) said: “So long as mankind thinks, there will be sects. Variation is the sign of life, and it must be there. I pray that they may multiply so that at last there will be as many sects as human beings, and each one will have his own method, his individual method of thought in religion... The greater the number of sects, the more chance of people getting religion. In the hotel, where there are all sorts of food, everyone has a chance to get his appetite satisfied. So I want sects to multiply in every country, that more people may have a chance to be spiritual... Our watchword, then, will be acceptance, and not exclusion. Not only toleration, for so-called toleration is often blasphemy, and I do not believe in it. I believe in acceptance. Why should I tolerate? Toleration means that I think that you are wrong and I am just allowing you to live. Is it not a blasphemy to think that you and I are allowing others to live?” Acceptance of all religions, sects or cults as true and valid means for attaining liberty, is the hallmark of Hinduism Weltanschauung, which makes a Hindu fundamentalist an oxymoron.