''They want you to use amulets and trust in the stars instead of using your reason. These holy men are holy fools tricking you. Be rational, use your minds,'' says Daun, as a rooster in the school grounds crows on cue as if to say ''hear hear''. Daun is one of three men in Mohali known as ''gurubusters''. He is talking to the schoolchildren, accompanied by his two colleagues, to teach them to spurn superstition and be rational instead. Daun is short and stocky and works as an Amway agent. His co-gurubuster Harpreet Rora is a slight, fresh-faced young man who works as a journalist. The third is the founder of the Mohali branch of the Indian Rationalist Association, the burly and avuncular Jarnail Singh Kranti, a retired primary school teacher. From a tiny office, using their own funds and their spare time, the endearing threesome, loyally supported by their wives, launch blistering broadsides against India's influential godmen. This is the headquarters of a lonely mission: promoting the supremacy of rationalism. Superstition is a multimillion-dollar industry in India. From the poorest to the richest, the predisposition to superstition is embedded in the neural pathway of most Indians. Choosing a spouse, fixing a wedding date, getting a job, trying for a baby boy, curing an alcoholic husband, reviving a failing business, curing an illness, ending a factory strike - all these problems require a visit to a holy man, who is paid a fortune for his services.

Gurubuster Satnam Singh Daun warns Indian school children about the trickery used by so-called gurus. Credit:Getty Images The propensity to believe that some mystic will solve your problems runs across the social spectrum. Former prime ministers have consulted bead-wearing astrologers on the most ''auspicious''' date for a general election. Bollywood stars offer tributes at the shrines of mystics to ensure a box office hit. Given their preference for discretion, wealthy Indians prefer to have a guru dedicated to their family; sometimes he lives with them so that he can be available at all times. ''I have total faith in my guru. He can cure cancer. I have seen it. I come away after an audience with him feeling light and blessed,'' says New Delhi garment exporter Rocky Verma, who has just asked his guru to suggest a date for his son's engagement.

Talk to the wives of tycoons and it becomes clear their faith in their family guru is blind. New Delhi art collector and gallery owner Renu Modi is married into the famous Modi business family and she is totally dependent on her guru, Swami Chandra. ''We do not make any major decision without first consulting him,'' she says. On Delhi's Prithviraj Road, home to many business moguls, Madhushree Birla, the wife of a scion of the Birla dynasty, sits in a living room full of priceless artefacts and talks of how she relies on Patrick, a Christian faith healer from Goa who she says can cure cancer. ''My faith in him stems from the day my brother and sister-in law were involved in a horrific car crash near Nasik. My brother had broken ribs and my sister-in-law suffered serious internal bleeding. ''Two minutes after they crashed, they were still lying there stunned but just beginning to realise what had happened when Patrick called them on the phone. He had seen everything that had happened and he knew what injuries they had suffered even though he was far away in Goa,'' she says. This is the kind of belief that Daun likes to pour his vitriol on. As the morning sun rises higher in the sky, he ignores the heat and starts getting into his stride, asking the schoolchildren, ''Has any holy man ever invented a medicine or an airplane? Can he stop any of you dying in a road accident? How can he help you do well in exams and get a good job when he himself is nothing but a failure?''

Standing behind Daun is his wife Neeraj. She hands him something. Daun pops a burning ball of fire into his mouth, eliciting gasps from the schoolchildren. Then he shows them that it is only burning camphor, which cannot hurt his mouth. He dips his hand into burning oil, unscathed, showing them later that he had pre-soaked his hand in oil as insulation. At the end of the talk, the children troop out to join their classes, having promised Daun that they will never again succumb to superstition. When they have finished handing out leaflets, the energetic gurubusting triumvirate pack their props, mount their scooters and head off to another assignment at another school to educate children on the importance of being rational. The Indian Rationalist Association was founded in 1949, with the good wishes of British philosopher Bertrand Russell. Its first members belonged to the educated elite. It has rarely had more than 100,000 members - mainly teachers, students and professionals - but they have been vigorous in publishing pamphlets and deriding the Indian penchant for superstitious nonsense. Over the decades, its branches have tried to inculcate Indians with a scientific temperament through debate, talks, ridicule, humour and challenges. Much of their time is spent performing the tricks that self-styled holy men love to perform to convince Indians of their special powers and to garner billions of rupees from their credulity. ''Their press conferences are hilarious because they consume fire, levitate (a trick requiring a blanket and two hockey sticks), walk on coals (the skin doesn't burn if you walk fast enough) and make statues 'weep' (melting a layer of wax covering a small deposit of water),'' says Mumbai journalist Neeraj Gaitonde. ''It's the only way to destroy the blind belief in their special powers.''

Some charlatans are more creative than others. One used to impress the crowds by ''creating'' fire by pouring ghee (clarified butter) onto ash and then ''staring'' at it until the mixture burst into flames. Rationalists-turned-detectives found that the ghee was glycerine and the ash was potassium permanganate and the two spontaneously combust a couple of minutes after they are combined. India's rationalists love to challenge quacks. When the well-known television guru Pandit Surinder Sharma boasted on television in 2008 that he could kill another man using only his mystical powers, Sanal Edamaruku, president of the Indian Rationalist Association (who is currently in hiding in Finland, but more of that later) took up the challenge and invited the guru to kill him on prime-time television. The guru agreed and appeared on television performing sundry rituals intended to kill Edamaruku. Millions tuned to the show. The hocus pocus went on for some time. The holy man ruffled the rationalist's hair, pressed his temples and mumbled incantations. Several hours later, Edamaruku was still alive, cheerfully taunting the frustrated killer. Edamaruku, a former journalist, became a rationalist activist when he was 15 after seeing a local athlete with blood cancer die because her family refused medical treatment, preferring a faith healer. Now he lives in Finland, having fled India after the Catholic Church in Mumbai filed a complaint against him in April 2012 under the country's blasphemy law. If convicted he would face three years in jail. The case concerned a crucifix dripping water at a Mumbai church. Edamaruku discovered the dripping was caused by a leaky cistern that was causing water to seep through the wall onto the crucifix. He reported his results on television and criticised the Catholic Church for being ''anti-science''. When the church filed a case against him, he fled.

Not so lucky was Dr Narendra Dabholkar, a prominent anti-black magic campaigner in Pune, near Mumbai, who was murdered on August 20. Known for his lifelong campaign against superstition, Dabholkar, 70, was gunned down during his morning walk. Dabholkar estimated that several hundred women are killed every year after being branded ''witches'' by so-called godmen. He also pointed out many children also were killed as part of ''human sacrifices'' ordered by godmen to resolve their followers' problems. Indians were shocked at the murder; some were equally surprised to discover that Dabholkar had been lobbying the provincial government of Maharashtra to approve the Superstition Eradication and Anti-Black Magic Bill to make superstitious practices illegal. Despite receiving several death threats from right-wing Hindu groups, Dabholkar refused police protection. These groups believed he was targeting their religion and not condemning superstition in all religions. However, the evidence suggests Hindu charlatans predominate (Hinduism in the largest religion in India), partly because there is no organised structure to the religion nor an established hierarchy, making it easy for anyone to set himself up as a guru offering spiritual advice.

Invariably, the majority of the controversial godmen who end up in the news for amassing millions, owning fleets of Mercedes and Audis, for being involved in prostitution rackets or are charged with sexual abuse or rape, are Hindu. Just last month, a leading godman called Asaram Bapu was arrested on charges of sexually assaulting a 15-year-old. Yet, seeing their godman behind bars has done little to dent the faith of his supporters. ''These godmen are like Jekyll and Hyde. They do a lot of social and community work initially to become popular before they start gratifying themselves,'' says Dr Indira Sharma, president of the Indian Psychiatric Society. ''They help with marriages, school admissions, medical treatment. So when they are charged with an offence, their supporters are not affected because they want to continue getting that help and it's in their interest to protect the godman.'' The Mohali gurubusters, always cheerful and energetic, have so far not received any threats.

''We won't stop, particularly when it comes to educating children,'' says Harpreet Rora. ''We want children to become ambassadors of change. They have to go home and tell their parents to stop their nonsense.'' The cost of superstition in India is high. All over the country, hanging in shops, homes, workshops and vehicles, are small bunches of green chillies and lemons tied together to ward off the evil eye and bring good luck. Fresh bunches are hung every day. ''Do you know that Indians spend 104 million rupees ($2.4 million) every year on buying chillies and lemons?'' says Jarnail Singh Kranti. ''At our local hospital, they have an astrologer on hand to 'help' patients if the medical treatment fails. This must stop. We must start relying on science and logic to move into the modern world.'' It is in the interests of Indian politicians, he adds, to keep Indians mired in superstition so that the poor don't start asking, ''Why are we poor?''

Before closing the shutters on the office, he points to a large poster hanging on the wall. It offers a reward of 2.3 million rupees ($39,000) to any godman who can perform any one of 23 acts, including standing on burning cinders for half a minute without blistering his feet; reading the thoughts of another person; making an amputated limb grow even one inch through prayer, spiritual powers, using holy ash, or giving blessings; walking on water; getting out of a locked room by divine power; or converting water into petrol. As he reads out the list, Kranti chuckles. ''We don't have 2.3 million rupees. But we're not expecting anyone to win so we're pretty safe,'' he says. Amrit Dhillon is a Delhi-based writer.