A) the belief that religion should not be involved in the organization of society, education, etc. (Oxford Dictionary)
B) the belief that religion should not be involved with the ordinary social and political activities of a country (Cambridge)
C) indifference to or rejection or exclusion of religion and religious considerations (Merriam Webster)
To the Congress Party, Secularism means appeasing Minority Religions. To the BJP it means, religious tolerance. To Narendra Modi, Secularism means, "Nation First"
Putting Nation First is not about patriotism, it is everything about 'Nationalism'.
To me, secularism has a big role in a state like India. We just cannot have religion dictating our laws, politics or governance.
Let there be reasoning, debates, dissent, common sense.