He began with talks on comparative religion, exhibiting a huge storehouse of knowledge that attracted a large number of Muslims and many non-Muslims too. But as his popularity grew, Zakir Naik turned Islamist, declaring non-Muslims as "disoriented", justifying sex with female slaves and calling upon Indian Muslims to refrain from saying "namaste".
Naik, now 50, is founder of the Mumbai-based Islamic Research Foundation (IRF) and Peace TV, which has over 100 million viewers. A doctor by training, Naik is now in trouble over allegations that his interpretation of Islam has radicalized young Muslims in India and beyond.
In his early speeches, Naik referred to popular misconceptions about Islam. In a 2006 talk, he even claimed that the "Kalki Avatar" in Hinduism was a prophesy for Prophet Mohammad. He drew parallels between jehad and Lord Krishna's call in the Bhagavad Gita to fight evil.
As the years rolled by, Naik turned against other religions, calling some hoax. Some, he told gatherings, were no religion. He quoted the Upanishad and other texts to claim that idol worship was against Hinduism.
Naik said it was wrong for Muslims to say "Namaste" or "Vande Mataram" and greet Christians with "Merry Christmas".
"The Bible has over 50,000 errors, it's unscientific," he declared in some lectures.
He made fun of Jesus Christ's sermon to offer the other cheek if slapped on one. He told a young Christian at one crowd: "It's baseless. Would you keep offering your cheek if we keep slapping you?"
At his gatherings, Naik would often bluntly ask questioners if he or she would embrace Islam if he answered their questions correctly. Some agreed and ended up changing their religion.
He said Muslims too could embrace other religions. But the punishment for this, he would quickly add, was "maut" (death).
Asked by a man if he considered Hindus as humans since he did not consider Hinduism as a religion, Naik replied: "If by Hindu you mean a geographical definition, then I don't have any problem."
"For peace to prevail, you have to follow the guidance of the Quran," he said while answering a question from a Jew at a conference in India.
Among Naik's other controversial teachings:
* "It is the duty of every Muslim to convey the message of Allah to non-Muslims." This comment triggered a ban on his entering the UK.
* He defended Osama bin Laden and called 9/11 an "American conspiracy".
* "If the word 'terrorist' means to terrorize the ememies or unsocial elements, then every Muslim must be a terrorist."
* "A Muslim can have sex with his wife or what his right hand possesses, which means a slave." He referred to slaves as "prisoners of war".
* Guantanamo Bay, which houses imprisoned terrorists, was holding "Muslim slaves".
* Asked why many Muslims become terrorists, Naik said: "It is a media strategy to malign Islam."
* Justifying polygamy, Naik said there were more women in the world than men and polygamy saved "extra women" from becoming "public property".
* Campaigning against pork, Naik argued that pig invited other males to have sex with his female mate. "Something similar happens in the Western society where they go to dance parties and do (wife) swapping." This, he said, was because Westerners ate pork.
As Naik's hate poison spread, he began to face bans in many countries including the US, Canada and the UK. He has also been denied permission in some Indian cities to hold meetings. And more than once, the Darul Uloom Deoband, India's largest and oldest Islamic seminary, issued fatwas asking Muslims not to go by Naik's sermons and teachings.
