She said the core of Nehruvianism is "democratic institution-building, staunch secularism, socialist economics and a non-aligned foreign policy.
"These were integral to his vision of India. Today, this vision is fundamentally under attack, but it remains at the core of the true India that we must continue to fight for," she said.
"Those who are in power today are blind to this truth. They lack the capacity, the vision and the wisdom to uphold this legacy. The forces unleashed by our present rulers want to dictate to us what we can do, say or think.
"Their idea of unity is uniformity. They disrespect and fear diversity, which means they deny our pluralism and freedom of choice, which are integral to our fundamental rights," Sonia Gandhi said.
The Congress leader said that those in power were speaking the modern language, but taking India backwards, not forward, because they have made no sacrifice to shape India's destiny.
"It falls on each and every one of us to pull away from this hypocrisy and reveal the darkness lurking beneath. We must unite and speak up against bigotry, injustice and mismanagement of the last six years, not just for ourselves, but also for the millions of our fellow brothers and sisters who continue to suffer," she said.
( With inputs from IANS )