Modi was not just an individual, Gandhi told the media here at an event where the Congress released its manifesto for the Lok Sabha election.
"The issue here is of an ideology that is quashing the fundamentals of what this country stands for, and that is what I am against," Gandhi said.
He said it was not a question of "personal like or dislike for an individual but the dangers represented by ths ideology".
Gandhi acknowledged that there were shortcomings in the Congress primaries held to pick Lok Sabha candidates but asserted that it was a powerful idea.
"Fifteen candidates have been chosen by primaries and this demonstrated that the decision on selecting candidates can be made by taking into account the inputs of a large number of party members," he said.