Accusing the Modi government of launching "systematic attacks" on institutions and causing divisions in the society, Gandhi said that after five years of Modi regime, the Congress' name was firmly entrenched in the minds of the people.
Gandhi, whose speech saw repeated thumping of desks by MPs, said that the results of the Lok Sabha battle will be a stunner.
"You will get a shock as to what is going to happen in 2019. This would not have been possible if you had not defended our position in Parliament," he said.
Attacking Modi over corruption, he said: "There is not a single leg for the Prime Minister to stand on. You can see it on his face, you can see the expression. The bluster has gone."
Gandhi said the Congress stood out among other opposition parties as it spoke for the country and it was the first to defend the idea of India.
"With respect to all my opposition friends, there is only one party that speaks for the entire country. Every other party speaks for a part of Indian society, and we say this with a lot of pride that we are the uniting party in this country."
Gandhi said BJP leaders were afraid to speak their mind.
"There is only one voice in the Lok Sabha in the BJP and that's Narendra Modi. Before they speak they think 'What is he (Modi) going to say, what is he going to think' and this is what is systematically being done."
Gandhi said the common man had realised that "Modi is not what he claimed to be, that the RSS is not what they claim to be".
He said modern India arises out of the Constitution.
"We see what is going on today and you can look anywhere. You can look at the Supreme Court, where four judges came out. It's being done to the Election Commission, it's being done to the defence forces, it's being done to Parliament. This is what you are fighting... And we are actually now winning," he said to cheers.
Gandhi also led a protest against the government in the parliament House complex. Former Prime Minister Manmohan Singh and Sonia Gandhi were among those who took part in the protest.