Markandey Katju made his comment in a lecture he was delivering in the central Indian city of Nagpur on the role of media in promoting secularism, organized by the Lokmat group of newspapers, the Times of India reported.
People should refrain from falling prey to religious nationalist politics, Katju, a former Supreme Court judge, said in his lecture.
"We must not be a Hindu nationalist or even Muslim, Sikh or Christian nationalist," he said.
"We must all be Indian nationalists. India is a country of diverse people and couldn't be run for a single day without secularism."
Katju said Pakistan is an example of a non-secular state that becomes mired in violence after independence.
British colonial rule over the Indian subcontinent officially ended at midnight on Aug. 15, 1947.
But there followed mass migrations, often accompanied by widespread violence, as Hindus in Pakistan and Muslims in India moved across the new boundaries, which often split the old Imperial provinces and states between the two new countries.
Subcontinent independence movements and the region's subsequent division were described in the 1965 book "Freedom at Midnight" by U.S. Newsweek journalist Larry Collins and French political author Dominique Lapierre.
"Look at the state of affairs in Pakistan," Katju said. "They wanted to have an Islamic state but it has turned into a 'Jurassic Park.'
"There are schisms between Punjab, Sindh or Balochistan provinces. Sometimes I feel it is not a country at all but just a creation of the British to divide Hindus and Muslims. India, Pakistan and Bangladesh should be reunited into one secular country," Katju said.
The dominant religion in India is Hinduism followed by Islam with around 13 percent of the population, amounting to more than 160 million people, 2001 census figures indicate.
India's media also must share blame for promoting nationalism and labeling all Muslims as terrorists, which alienates them from mainstream Indian society.
Too many news organizations accept the validity of text messages on phones and emails allegedly from terrorist organizations such as the Muslim group Jaish-e-Mohammed or the Indian Mujahedin claiming responsibility for bomb blasts.
"This demonizes the entire Muslim community," he said.
"An email or SMS can be sent by any mischievous element. In fact, 99 percent of people in all communities are generally good."
But reality is the majority of Indians remain uneducated and steeped in communalism, leading them to vote on the basis of caste or religion, he said.
Katju is a former labor lawyer and was noted as one the country's fastest, at one time disposing of more than 100 cases in a week, a report by India Today in 2011 said.
Katju, 66, also is no stranger to controversy, despite his anti-nationalist and anti-violence stance.
In December, he said the vast majority of Indians are "idiots" who are easily led, ZeeNews reported.
"I say 90 percent of Indians are idiots.You people don't have brains in your heads. ... It is so easy to take you for a ride," he said at a seminar in New Delhi.
A simple mischievous gesture of disrespect toward a place of worship and people of different religions start fighting each other, he said.
"You mad people will start fighting among yourselves not realizing that some agent provocateur is behind this," he said.
Katju's latest comments come as the Hindu nationalist Bharatiya Janata Party recently chose the controversial and polarizing leader Narendra Modi to head its campaign in federal elections.
BJP, a major Indian political party at state and federal levels, was set up in 1980 to protect the rights of the majority Hindu religious group.
Modi is also chief minister of the western state of Gujarat and is popular among upwardly mobile, urban middle-class Indians.
But his critics accuse him of not doing enough to quell religious violence when it breaks out.
Human rights groups accuse Modi of not making an effort to stop mobs from targeting Muslims in reprisal attacks after 58 Hindu pilgrims and activists died in a 2002 train fire that Muslims were suspected of starting. More than 1,000 people, mostly Muslims, died in the violence.
Earlier this month, a senior member of the BJP in Tamil Nadu state was hacked to death inside the compound of his home in Salem, a city in the southeastern state.
The leadership of the BJP in Tamil Nadu claimed police haven't been taking seriously their calls for protection in the face of targeted attacks.