Part III of the Constitution deals with Fundamental Rights.
Articles 25 to 28 deal specifically with Freedom of Religion.
Article 25 – Freedom of conscience and free profession, practice and propagation of religion
Article 26 – Freedom to manage religious affairs
Article 27 – Freedom from paying taxes for promotion of any religion
Article 28 – Freedom as to attendance at religious instruction in certain institutions
These ensure India remains a secular country while protecting religious rights.