Speaking after the release of a book, "Vision for a Nation: Paths and Perspectives", he said if one is secular these days their patriotism will be questioned and there will also be people who will, in course of time, question citizenship of others which is a point of danger.
The book brought out by Samruddha Bharat Foundation was earlier released by former prime minister Manmohan Singh and former vice president M Hamid Ansari, besides Chidambaram and others.
Chidambaram said that many Indians have become diminished citizens these days and while there are many propagating Mahatma Gandhi's concept of civil disobedience against injustice, there are also people propagating Adolf Hitler's philosophy of demanding complete obedience to the supreme leader.
The Congress leader said one of the fundamental ideas of a modern democracy is secularism and it is under challenge along with citizenship today. He said secularism is being challenged to a point where citizenship has also become an object of attack.
"We have reached a point where the debate on secularism has shifted to a debate on citizenship".
"If you are secular today, there are people who will call you anti-national, if you are secular today, they will say that you are speaking the language of Pakistan, if you are secular your patriotism is under question. Many of these people will have the citizenship of others under question in course of time. That is the point of danger at which we seem to be arriving at in the last few years," he said.
Citing an article in the book, Chidambaram said concepts both of Gandhiji and Hitler are being witnessed today in society.
There was a time when Gandhi came up with the idea of civil disobedience as a statement of one's moral courage in the face of injustice, he said.
"I am proud that the people who, we thought, will not come out of their homes in this cold are now actually practising Gandhiji's civil disobedience.
"On the contrary, Hitler's view was demanding complete obedience to the views of the supreme leader. There are examples today in India, in Delhi of civil disobedience as a statement of one's moral courage against injustice. We also have examples of people demanding complete obedience to the supreme leader," he said.
The former home minister said people's citizenship seems to have been diminished by a number of things and in a digital world, if one is denied citizenship for seven months, one is diminished as a digital citizen.
"What is happening today is that it is only if we speak a particular language, speak the language belonging to a family or we belong to a race, or we belong to a religion or we practice a particular culture, that we will be an Indian citizen.
"If this definition is applied, many of us will cease to be citizens, many of us will become diminished citizens. A large number of us will even become non-citizens. As long as this was simply a theoretical idea propagated by Savarkars or Golwalkars, there was nothing wrong.
"But, when this becomes a political project and the state is willing to put its power, resources and might behind taking this political project forward, we should seriously worry about what will happen to the concept of constitutional citizenship devised by Dr Ambedkar and Jawaharlal Nehru," he said.
Chidambaram alleged that politicised religion has almost taken over this country and over its institutions. Many of the institutions have been captured by those who belong to a particular religion, he said.
"If you don't belong to this religion, or even if you belong to this religion and do not belong to the politicisation of this religion, then you have no place in many of the institutions of India of today," he said.
Another Congress leader Shashi Tharoor said a final assault is underway on the foundational ideas of the country and there is need for a parallel paradigm, and it has become indispensable to re-articulate ideas and to convey them to the people.
"This government prefers uniformity over unity in the country...they are redefining and reactivating the idea of India," Tharoor said.
CPI general secretary Sitaram Yechury said, "We are at a defining moment of what would be of the Republic of India". "Any effort to impose uniformity would lead to an implosion," he said.