Two constitutional provisions that make India a secular state are:
Source: Democratic Politics II, Chapter 3, "Secular State"
The question directly matches Exercise Q.6 from the chapter. Examiners expect two distinct provisions clearly stated. The most commonly accepted points are: (i) no official/state religion, and (ii) freedom to profess/practise any religion + prohibition of religious discrimination. You may also mention that the state can intervene to ensure equality within religious communities (e.g., ban on untouchability) as an alternative second point.