The actor Farooque Shaikh said on a discussion show on television recently that no religion claims to be absolute. Chandan Mitra, the journalist, added that all religions preach tolerance. The two gentlemen were not unusual in uttering this pious rubbish. All those people say this who do not ever trouble to question religions but only wish them to coexist peacefully. They treat religions much as they treat Nature itself: like immutable givens. They speak out of habit, merely regurgitating received wisdom. They speak without applying their minds.

Shaikh was of course entirely wrong. The fact is that every religion claims to be absolute, to be the Ultimate Truth. If it did not make such a claim, it would be left with nothing to stand on. Every religion is by definition unquestionable and not subject to the usual rules of reason, evidence and proof. Every religion demands of its followers unquestioning faith. This act of surrender to the divine has been romantically glorified over the centuries, in all religions and in literatures across the globe, but equally we could argue that such surrender reduces otherwise thinking, acting people to brainless, spineless, grovelling supineness.

Mitra may have been right in saying that all religions preach tolerance. After all, tolerance is a Good Thing, and it would be a strong and foolish religion which could resist the urge to make a claim to it. But claims can be tall. We must go on to analyse if any religion does or even can practise this tolerance business. Such statements are sometimes made by people who actually are saying, "Look how grand and good and liberal we are. See how much better our religion is than those other ones."

Sparing the life of a vanquished enemy is a fine chivalrous gesture. But if it is known that the enemy will never change his colours, that he will remain an enemy to be feared, then the fine gesture reveals itself to be a foolish and suicidal one. Real life is not Sikandar and Porus, it is not Arthur's Round Table. It is religions butchering one another.

Can religions coexist peacefully? I believe they cannot, because two alternative absolutes must inevitably come into conflict: neither can be accepted without automatically denying the other. They might trundle along side by side for years or centuries, but when push comes to shove they are bound to be pitted against each other. All this talk of religious tolerance is the purest humbug.

No system of beliefs which considers itself absolute and unquestionable can accept the existence of another system of beliefs which makes the same claims. As a kingdom cannot have two kings, so a world cannot have two gods – just as, to give an example which will be readily understood today, a corporation cannot have two CEOs. There can be only one absolute, one single point at which everything converges and stops.

Another journalist on the same show, Dileep Padgaonkar, edged nearer to the truth in saying that each religion had at its core a system of ethics, of definitions of good and bad; but he stopped short of noting that each religion justified these definitions by reference to one or other unquestionable absolute.

That a man should not pull his brother-in-law's moustache is a perfectly sane and sound principle. But if someone were to question me on the reason for it, I would not give the rational answer: that moustache pulling can be painful and depilating and, when it happens among relations, can lead to the disintegration of the kinship network. Instead I would produce a cock-and-bull story about mythological characters or divinities who created trouble for themselves by engaging in the sport. The story will be swallowed whole, for the reason that by definition it may not be questioned.

What is to prevent me, once I have tasted success, from setting out other principles, each with its backing story which will be believed because not believing is not an option? It is not a characteristic of humankind to leave well alone, to not exercise a power which one has seen oneself to possess. I can make up principles about beef or pork or menstrual blood or alcohol or urine. In time I shall have a rule for a person's every waking moment, for every conceivable situation in which people can find themselves. This is just what religions have done through history. Each religion has built up a body of rules and principles to cover all eventualities. Should a new situation arise, there are precedent analogues enough for it to rummage in its grab bag and produce something to fit. If there are no analogues, it can simply concoct a new rule, knowing that that will be accepted on the basis of the acceptance given to so much else.

The bag is, of course, sacrosanct: all that comes out of it is by definition correct and may not be challenged. My birth into religion X obliges me to swallow all the tenets and rules of that religion with my eyes closed, never mind what my reason tells me, never mind that millions of people – who are essentially like me, certainly neither better than me nor worse – go about swallowing different sets of tenets and rules.

It is this acceptance of something without demur or question, this justification of principles by reference to supra-rational sources, which reduces the basically sound ethical system of a religion to a travesty. It has happened, in every religion, that the sound core of the ethical system has had added to it a mass of rules which are nowhere near as sound. This shrubbery, this ornamentation, these bodies of "hanger-on" principles, may have been born of historical accidents or even of the idiosyncrasies of historical figures who were important in the religions in question. That is a matter for speculation. What is important is that each of these non-essential "principles" is absolute, even the one that I should not pick my nose in the dark while facing north-west; or east or south-east, as those other religions have it.

Religions are all many centuries old. The believer today has no way to tell myth or fairy tale from religious teaching devised by people who had a grasp over realities and wanted to protect the followers of their religions from dangers. Under-cooked pork can cause trichinosis, for example, so pork and the meat of all cloven-footed animals is banned. The faithful are told that the ban has a divine origin, precisely because that justification is quicker and simpler than a rational one, and because it is absolute.

Yet the pig is an important part of the diets of many peoples who are in no way behind those who forbid the eating of pork.

Equally, later developments may supplant and obscure earlier realities. Beef was eaten in Vedic India, for the reason that cattle were reared and therefore available. But along the line vegetarianism was imposed ex post facto on ancient India and the cow somehow became holy (though not that other profusely lactating bovine, the water buffalo) and so may not be eaten but has the right to freely obstruct road traffic. (I do not think the prospect of bovine spongiform encephalitis, "Mad Cow Disease", far in the future and on another continent, was the original reason for the ban.) A large body of myths and legends surrounding the cow has built up over the centuries. Today the animal has come to be associated firmly with gods and goddesses and sages, and who would dare to question divinities and quasi-divinities?

Yet many peoples, in no readily apparent way inferior to the cow venerators, routinely dine off that creature. (Some even attribute to it an absence of intelligence, as seen in the insult commonly traded between human females: "Stupid cow.")

Is India a secular country, as common wisdom holds it to be? No, it is not: it is merely a multi-religious one. The two ideas have been confounded so thoroughly that we no longer know the difference. "Secular" means lay, of the world, not pertaining to religion. A country or society cannot be described as secular just because it is home to not one religion but many. To be secular in the full sense, it must have no religion at all. In practice, of course, it is usually considered sufficient if religion does not intrude into the area of civil life.

But in Indian politics we have an excellent example of just such an intrusion. All politics is not necessarily bad, as some with anarchist tendencies hold: what is bad is politics tainted by religion. Throughout history, across the world, religions have sought to wipe out other religions because all have invaded the space of political power and have twisted that power. Each religion has warped political power by implicitly or explicitly declaring its own expression of it justified by an unquestionable absolute.

This is the road of irrationality, and it leads inevitably to murder and war and, as we saw recently in Gujarat, to genocide. In this last example, the State in the province, required by the Constitution to be secular, was blatantly religious. Its functioning was dictated by one religion and its actions and its inaction were aimed at the destruction of another religion. Whatever the framers of our Constitution may have meant by secularism, certainly it was not this.

The future of our country has been questioned in a fundamental way, and one of the paths open to us – along which some lunatic barbarians wish to drive us – has been shown to us with great clarity. If that is not the path we wish to take – and no sane person can want that – we must decide very soon and very firmly just what is the role we shall allow to religion. If religion is allowed to define and dominate State, disaster is the certain consequence. The Vedic Taliban will grab power, and its rule will be bloodthirsty and aeons away from any kind of rationality.

Rationality is the key. Over the millennia, humankind has advanced in every field because of the growth of rationality – except in religion, where there simply is no space for it.