Sonia Gandhi said secularism was an article of faith for Jawaharlal Nehru.
The Congress celebrations on the 125th birth anniversary of Jawaharlal Nehru on Monday provided a platform for the coming together of several non-BJP parties - among them arch-enemies Trinanool Congress and the Left.
The Congress had pointedly excluded Prime Minister Narendra Modi from the guest list, which had several world leaders including former Afghan president Hamid Karzai and former foreign minister of Egypt Amr Moussa.
While the BJP strongly criticised the disrespect shown to the Prime Minister's Office, Congress chief Sonia Gandhi made it clear that it was an assembly of 'like-minded secular parties'. Some Congress leaders argue that the BJP never invited Former Prime Minister Manmohan Singh for any of their functions.
Underscoring secularism was an article of faith for Nehru, Mrs Gandhi, who is also her grand daughter-in-law, said, "There could be no Indian-ness, no India, without secularism".
"Secularism was and remains more than an ideal. It is a compelling necessity for a country as diverse as India," she added.
West Bengal Chief Minister Mamata Banerjee, who is trying to contain a BJP surge in her state, responded, saying, "I don't believe in communal politics. It (communalism) is the number one enemy. We have seen (communal clashes) in Uttar Pradesh, Bihar and Gujarat. Even in Bengal, they are trying (to trigger clashes)."
At the function, Ms Banerjee had shared stage with senior CPM leader Sitaram Yechury and CPI's D Raja.
Former Prime Minister and JD(S) chief HD Deve Gowda, JD(U) chief Sharad Yadav, NCP leader DP Tripathi and RJD's Jaiprakash Yadav were also present on the occasion.
Calling it a coming together of "disparate elements", Union Minister and senior BJP leader Arun Jaitley wrote in his blog, "Those who rejected Panditji's politics in his lifetime, are a part of the "show of strength" at this symposium".
"Dr Ram Manohar Lohia... rejected Panditji's politics during his lifetime. The Left's anger against Panditji was further fuelled by the invocation of Article 356 to dislodge the first ever democratically elected Communist Government led by Shri EMS Namboodripad in Kerala," he wrote.