The victim says an Orthodox priest in Kerala raped her as a minor in the 1990s. Subsequently, three other priests allegedly blackmailed and raped her, the unnamed woman told investigators.
Indian police said on Tuesday they were investigating four Christian priests for allegedly raping and blackmailing a woman in a cycle of abuse and threats lasting almost 20 years.
The woman told police that her ordeal began while still a minor in the 1990s when an Orthodox priest at a church in the southern state of Kerala forced her into sex.
She confessed to a second priest, who allegedly blackmailed her into having sex with him. A further two priests also threatened her and forced her into sex, the woman, who has not been named, told investigators.
"We filed a case on Monday based on her complaint. We have now started our investigation," local police official S Sreejith said.
Her alleged suffering only came to light after an audio clip of her husband complaining to a church official went viral on social media, media reports said.
The Christan community in India, as elsewhere around the world, has been rocked by sexual abuse allegations.
Last year, a pastor accused of raping two women on the pretext of driving out evil spirits was arrested in eastern India.
In 2016, an Indian priest was sentenced to 40 years in prison for raping a 12-year-old girl.
Christianity is India's third-biggest religion according to the 2011 census, with approximately 28 million followers or 2.3 percent of the population.
Sexual violence is rife in India with nearly 40,000 rape cases reported in 2016, which activists say is the tip of the iceberg as most cases go unreported.