New Delhi (CNN) Thousands of police have been deployed in the southern Indian state of Kerala as a centuries-old temple at the center of an ongoing, and sometimes violent, gender dispute prepares to open its doors for the annual pilgrimage season.

For centuries, women aged 10 to 50 were not allowed to enter the Sabarimala Temple . But in September last year, the country's Supreme Court overturned the ban, and in January, women entered the temple for the first time, defying opposition from religious conservatives.

But that decision is now in question, after the Supreme Court agreed Thursday to review its landmark ruling.

It's unclear whether women will be allowed to enter the temple when it opens its doors Saturday, although the Supreme Court said Thursday that its September 2018 decision -- that the ban on women entering was discriminatory -- remained in force.

Around 2,500 police were deployed Saturday -- and more may be deployed if required, Lokanath Behera, the Director General of Police in Kerala, told CNN Friday.

During the last pilgrimage season in January, violent protests erupted across Kerala state, leaving at least one person dead and prompting police to deploy tear gas and a water cannon. Women who tried to enter the shrine were told to go back and, in some cases, assaulted.

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In its decision Thursday, the Supreme Court ordered the state government to "take steps to secure the confidence of the community in order to ensure the fulfillment of constitutional values."

"Organized acts of resistance to thwart the implementation of this judgment must be put down firmly," the ruling added.

Rahul Easwar, a right-wing Hindu activist who petitioned to overturn the September 2018 ruling, called Thursday's decision a "step in the right direction."

"There is an implicit admission that the earlier verdict should be reviewed," he told reporters Thursday. "We hope that the Sabrimala culture and belief will be protected."

In September 2018, the ban was reviewed by a five judges -- it will now be sent to a seven-judge bench for consideration.

Why was there a ban on women?

The Sabarimala shrine, thought to be more than 800 years old, is considered the spiritual home of Lord Ayyappa, a Hindu god of growth.

Supporters of the ban on women of menstrual age argue that since Ayyappa is considered celibate, allowing "impure" women into the temple is disrespectful.

Devaswom Minister Kadakampally Surendran has said that Sabarimala is not a place for activists to display their activism and said the government would not encourage such women who want to visit the shrine for publicity. Those who want to visit the temple can procure a court order to enter the temple, he said.

But people who oppose the ban say that it was a form of discrimination done in the name of tradition.

In this photo taken on January 2, 2019, India police disperse activists trying to burn an effigy of Kerala's Chief Minister Pinarayai Vijayan, at a protest after two women entered the Sabarimala Temple.

Earlier this year, Subhashini Ali, a member of the Indian Communist Party that governs Kerala and a participant in the protest, said women fighting for their rights to access the temple would "change the conversation around gender."

"It is an issue important for women and democracy," Ali said.

In January, Bindu Ammini, a law lecturer, and Kanakadurga, a local government employee, made history when they became the first women to enter the shrine after the ban was lifted.

The temple was later closed for an hour to allow priests time to purify the site following their visit.

The pair had previously attempted to enter the temple in December but were stopped by mobs of angry hardliners shouting and blocking their path. After Ammini and Kanakadurga visited in January, both went into hiding.

A long history

The Supreme Court judgment allowing women inside the Sabarimala Temple was the culmination of a decades-long battle.

The prohibition was first challenged before the Kerala High Court in August 1991, with the high court ruling that only a priest could make the decision on allowing women access to the site.

Prime Minister Narendra Modi appeared to side with the conservative protesters who want to bar women from the temple. In an interview with Indian news agency ANI, Modi pointed to the fact that some temples do not allow men inside, though he did not cite specific examples.

Indian Hindu devotees take part in a protest against a Supreme Court verdict revoking a ban on women's entry to a Hindu temple, in Thiruvananthapuram in southern Kerala state on October 15, 2018.

Modi's Bharatiya Janata Party (BJP) has previously voiced opposition to the Supreme Court's decision.

Amit Shah, the leader of the BJP, has characterized the debate as one between people of faith and an oppressive state government in Kerala.

The BJP has historically espoused Hindu-nationalist positions, and some of its more extreme candidates have been accused of being anti-Muslim.