Attack comes just months after gang-rape of elderly nun.
The 47-year-old nun of the Salesian Missionaries of Mary Immaculate was attacked early morning of Saturday in a dispensary the nuns run.
Christian leaders suggested the attack was a part of targeting Christians.
“It should be seen as part of the ongoing attacks on religious minorities," said Father Sebastian Poomattathil, vicar general of Raipur archdiocese.
"It is targeted. They came prepared and did not disturb the other two women in the building," he said.
Fr Poomattathil said local parishioners held a public protest on Saturday and Sunday, with more than 3,000 people attending Sunday's rally in the city.
The leaders have also submitted a memorandum demanding the arrest of the perpetrators within 72 hours.
"If they fail to arrest the culprits soon, we will intensify the agitation and spread it across all parts of the state," he added.
Jayanti Singh, a gynecologist that examined the nun at the scene of the attack — the nun’s bedroom in a small medical dispensary — said two masked men broke into her room, tied her up and attempted to rape her.
"There were semen-like secretions on her private parts and stains on her clothes," said Singh, who added that it appeared to be an attempted rape and said she could not say for certain without the official police report.
Sister Annies John, the nun’s superior, said the victim was wakened by the sound of cupboards being opened. The victim asked if they were looking for money, Sr John said.
“We need money, but something else also,” Sr John quoted the attackers as saying, according to the victim.
Sr John added that the attackers forced the nun to swallow a tablet before trying to rape her, though the nun believes she successfully fended them off.
“She was hardly conscious by that time but believes she successfully foiled the attempts,” Sr John said.
A fellow nun discovered the victim at around 6am, after which police brought her to a government hospital.
"She was screaming and yelling soon after she was released from the bed. She was obviously disturbed and will take some time to recover," said Sr John.
Both Sr John and Singh said it was impossible to say for certain if the nun had been raped until a police medical report is issued. Multiple attempts to reach the police went unanswered Monday.
The attack comes three months after a 71-year old nun was gang-raped near eastern Kolkata city.
Police arrested migrant Bangladeshis but Church leaders suspect they are scapegoats and that Hindu hardliners are behind the attack.
The Catholic Bishops Conference of India (CBCI) said it "views these attacks on the nuns very seriously" and urged the federal and state governments "to act speedily to book the culprits involved in this heinous crime".
Such incidents of violence against minorities, and especially women, tarnish "the image of our country in the international community, besides posing serious questions as to how far the minorities are safe and secure today in India," said a statement issued by the CBCI’s general secretary Archbishop Albert D'Souza.