Secular State .. India is a secular state.
1. It does not have an official religion, unlike Pakistan, Saudi Arabia, Iran etc. Islam is the official religion there. The latter are called theocratic states.
2. India treats all its citizens equally. Showing favour to a citizen or punishing him for any offence more than others just because he belongs to any particular religion is not allowed in law. Whether one is a Hindu, or a Christian, or Muslim, one would get the same favour from the state as others. Similarly, for committing a crime, people will get the same punishment. The judge can not favour or disfavour any one on the basis of religion.
3. The Constitution has articles that define relations between citizens and their government. It has no clause to define how would one pray, to which God, and what reward one would get for belonging to a certain faith.
4. Thus, in governance, religion plays no part at all. But, the Constitution does not ask a citizen to become an atheist and give up one’s religion. Religion is treated as a personal and private matter.
5. The 42nd Amendment to the Constitution made communal speeches and writing (that spreads hatred and disharmony among followers of different religions) illegal and punishable under law.
6. Schools can be started and run by minority communities, where their scriptures and philosophy are taught, but they can not force the students to take part in any form religious instruction. They can not refuse admission to students belonging to other religions. Thus a school run by Muslims can impart Islamic education, but can not force the unwilling students to do Namaz.