Police said the suspect, named as Gangeshananda Theerthapada, would come to the woman's house to perform prayer rituals for her father's health.
Her mother had hoped the self-styled holy man would ease the family's woes.
Instead, her daughter claims he assaulted her at every opportunity.
On Friday night, she grabbed a knife and attacked him when he allegedly tried to rape her, and then called the police herself.
The alleged rapist was rushed to Thiruvananthapuram Medical College for emergency surgery.
