This chapter examines the rise of Hindutva nationalism in India and how it affects secularism and religious freedom in the country. It studies how the movement has gained major political and social influence in the last decade leading to increased extremism. The chapter explores how Hindu nationalism is propagated by political parties, cadre organisations, schools and media. This is causing the gradual radicalisation of the Indian youth and eroding India's secular foundations by threatening religious minorities. The chapter reviews relevant literature and cases to present the mainstreaming of Hindu nationalism and its impact on governance and societal cohesion. The chapter concludes with recommendations to reinforce secularism to counter the impact of religious radicalisation.