One recent morning, Roop Rekha Verma, an 80-year-old peace activist and former university leader, walked through a north Indian neighborhood prone to sectarian strife and parked herself near a tea shop.

From her sling bag, she pulled out a bundle of pamphlets bearing messages of religious tolerance and mutual coexistence and began handing them to passers-by.

“Talk to each other. Don’t let anyone divide you,” one read in Hindi.

Spreading those simple words is an act of bravery in today’s India.

Ms. Verma and others like her are waging a lonely battle against a tide of hatred and bigotry increasingly normalized by India’s ruling Bharatiya Janata Party, or B.J.P.

As Prime Minister Narendra Modi and his deputies have vilified the country’s minorities in a yearslong campaign that has escalated during the current national election, the small band of aging activists has built bridges and preached harmony between religious groups.