Facing Bharatiya Janata Party's PM candidate Narendra Modi as the main opponent, she said secularism was a matter of deep faith for the Congress and not a matter of political compulsion.
In 20-minute speech, she also touched on the issue of corruption, a major issue stalking the UPA II government, appealing to parties to rise above political considerations to ensure passage of anti-corruption measures pending in Parliament.
"The biggest threat before the country is from communal forces and ideologies. Congress stands for uniting the people...but what is the approach of our main political opponent I will tell you. You know it yourself.
"It is to divide the society on communal lines and spread hatred in the name of unity to impose a single identity.
They hide their real face behind the mask of moderate pretensions. They criticise our leaders and level false allegations against them and they go to the extent of spreading violence. How can such an ideology be tolerated," Gandhi said addressing the day-long AICC session here without naming Bharatiya Janata Party.
Prime Minister Manmohan Singh, Rahul Gandhi, senior cabinet ministers and party leaders from all over the country heard her in rapt attention as she spoke of the successes of the UPA coalition.
She said the Congress workers should be proud that the party never compromised on its ideology. "For Congress, secularism is not a political compulsion but a matter of deep faith," she said.
Describing secularism as the biggest identity of the country, Sonia Gandhi hit out at the BJP, without taking its name, saying the policy of the main opposition party is of dividing society on communal lines, imposing uniformity in the name of unity.
"The biggest danger to the country's social fabric is from the communal forces and their ideologies. Congress has always worked to unite people and has never compromised with communalism. Secularism means equal faith in all religions (sarva dharma sambhava). It is not an electoral compulsion for us. This is something which we deeply believe in," she said.
Striking a similar note, the omnibus resolution moved by senior leader Ghulam Nabi Azad and seconded by P Chidambaram for consideration at the AICC meet said, "the recent political setbacks are an important wake up call" underlining the need to enhance the connect with people and work harder.
"The next elections will see a sharpening contrast between competing ideologies from the past and clashing vision of the future. It will be a battle between forces of age old secularism and others. It will be a battle for India as we cherish," she said.
Seeking to contrast it with the politics of BJP, she said their way of functioning is to divide society on communal lines and provoke violence. "As Congressmen, we have always fought this ideology."
"The 2014 Lok Sabha elections is a contest between opposing ideologies - one that seeks to divide and other than seeks to unite India. One a polarising ideology that militates against the core values which define Indian nationhood and its constitutional democracy and the other a liberal secular democratic ideology represented by Indian National Congress," the resolution said.
Gandhi said despite false allegations levelled by the opposition, the UPA government stood ground and remained firm in taking decisions which were pro-people.
Referring to the rich-poor divide, the Congress President said while economic growth is essential, "it alone cannot address the problem of disparity."
She said in the last one decade since UPA came to power, the party as well as the government have "responded to the stress" and taken various key policy decisions.
She said the UPA can "justifiably take credit" for the decisions it took to improve the state of the economy.
However, she did not shy away from accepting that while there had been an impressive economic growth, disparities in the society also remained.
Gandhi said the Congress-ruled states will implement the Lokayukta Act, based on the Lokpal and Lokayukta Act passed by Parliament, by next month.
She also gave the Congress party credit for the historic Right to Information Act as she said that "transparency lies in the solution to fight corruption".