The world’s most unexpected megachurch pastor might be an illiterate, barefoot father of five.

Bhagwana Lal grows maize and raises goats on a hilltop in Rajasthan, India’s largest state, famous for its supply of marble that graces the Taj Mahal. He belongs to the tribals: the cultural group below the Dalits, whose members are literally outcasts from India’s caste system (and often called “thumb signers” because of how they vote).

Yet every Sunday, his one-room church, with cheerful blue windows and ceiling fans barely six feet off the ground, pulls in 2,000 people. His indigenous congregation draws from local farmers, whose families’ members take turns attending so that someone is tending the family’s animals. The cracks in the church’s white outer walls are a source of pride: They mark the three times the building has been expanded.

Thousands of colorful flags stream down the sanctuary along the blue beams that support the corrugated metal roof. Their rustling approaches a roar.

When asked the reason for the flags, Lal responds, “For joy!” laughing heartily. The decorations are normally used at weddings. “The same feeling should be inside the church. People should feel this is God’s place.”

Yet consider a contrasting megachurch in southern India. A taxi drives under the shadow of Hyderabad’s four-story elevated train, whose massive support beams are marked with alternating colorful gods and goddesses. The roadside, lined with movie posters and squatter tents, gives way to clusters of large stone elephant-headed gods waiting to be painted with customary bright colors. The taxi turns into a dense traffic jam: a mile-long jumble of buses, motorcycles, ...

1