Speaking at an international conference organised by the Congress to commemorate the 125th birth anniversary of India's first prime minister, Gandhi made veiled attacks on the BJP, saying Nehru's life and work had been "drowned out by misinterpretation and distortion in recent years".
Prime Minister Narendra Modi was not been invited to the two-day meet. West Bengal Chief Minister Mamata Banerjee and Communist Party of India-Marxist leaders Prakash Karat and Sitaram Yechury and Janata Dal-United chief Sharad Yadav were among those present.
Also those present were former Afghan president Hamid Karzai, former Ghana president John Kufuor, Queen Mother of Bhutan Ashi Dorji Wangmo Wangchuk, former Nepal prime minister Madhav Nepal and former foreign minister of Egypt Amr Moussa.
Gandhi said that although Nehru was socialist by conviction, he valued individual liberty above all else. Gandhi said secularism was an article of faith with Nehru.
"If any person raises his hand to strike down another on ground of religion, I shall fight him to the last breath of my life as head of the government and from outside," she quoted him as saying.
The Congress president said there could be no Indianness and no India without secularism. "Secularism was and remains more than an ideal. It is a compelling necessity in a country as diverse as India."
She took potshots at the Bharatiya Janata Party at the start of her speech.
"Jawaharlal Nehru once remarked that wealth shouts but knowledge whispers. That whisper of knowledge about Nehru's life and work has weakened in recent years in our country, drowned out by misinterpretation and distortion. Yet the ideas he promoted and the values for which he stood remain all the more relevant," Gandhi said.
Sonia urges workers not to feel dejected
She said Nehru was once compared to a sculptor, called upon to work on a massive block of granite encompassing one sixth of the human race. "Out of that block of granite, Nehru built a state, a nation, a democracy. He nurtured democracy as a mother nurtures her child."
After the Lok Sabha debacle and further electoral shocks in Haryana and Maharashtra, Gandhi sought to urge party workers not to feel dejected saying they were on the right path.
She said Nehru had said on the eve of first general election that people had to know how to win and lose with grace.
"Those who win should not allow this to go their heads, those who lose should not feel dejected. The manner of winning or losing is even more important than the result. It is better to lose in the right way than to win in the wrong way," she quoted Nehru as saying.
Gandhi said India's democracy has evolved over the last 50 years sometimes in ways that would have surprised Nehru.
She said Nehru's belief that only parliamentary democracy and a secular state could hold a diverse country together had been proved right.
Nehru was right about the consequences of allowing religion to seep into politics, she added.
"The truth of his conviction can be seen in the conflicts raging in various parts of the world in the name of religion."
Describing Nehru as one of the greatest Indians, Gandhi said he was a man of many parts, a man of ideas and a man of action, a man of letters, a synthesis of the best of the East and the West, and an ardent nationalist who was also a fervent internationalist.
The theme of two-day conference is "Nehru's world view and his Legacy - Democracy, Inclusion and Empowerment".
Leaders from the Nationalist Congress Party, Rashtriya Lok Dal and Rashtriya Janata Dal attended the meeting but no senior Samajwadi Party leader was present.