A group of mostly Hong Kong-based academics, lawyers and human rights activists has warned that regularizing seven illicitly ordained bishops in mainland China would cause Catholics in the country to “be plunged into confusion and pain, and schism would be created in the Church in China.”

The open letter was addressed to the bishops’ conferences of the world, and said the signatories were “shocked and disappointed” about unconfirmed news reports claiming the Vatican and China are on the brink of an agreement on appointing bishops in the country.

The proposed agreement would allow the communist regime to nominate bishops, subject to a Vatican veto. Part of the deal would be allowing seven bishops already appointed by the government – and excommunicated by the Vatican – to be regularized and recognized by the Holy See.

The open letter calls on the world’s bishops to appeal to the Vatican to “rethink the current agreement, and stop making an irreversible and regrettable mistake.”

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Two “underground” bishops have already been asked by the Vatican to step aside for their government-appointed counterparts, and on Sunday, one of the bishops, Joseph Guo Xijin of Mindong in Fujian Province, said he would acquiesce to the request.

“Our consistent stand is to respect the deal made between the Vatican and the Chinese government,” Guo said before evening Mass, according to the New York Times. “Our principle is that the Chinese Catholic Church must have a connection with the Vatican; the connection cannot be severed.”

The bishop also expressed his view that in recent years the government has “loosened up” when it comes to religious affairs.

So far, 88-year-old Bishop Peter Zhuang Jianjian of Shantou in southern Guangdong province has not agreed to step down.

The deal has been sharply criticized by the former Bishop of Hong Kong, 86-year-old Cardinal Joseph Zen, who has accused the Vatican of “selling out” the Church in China.

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The Chinese Patriotic Catholic Association was established by the Communist government in 1957 to oversee Catholic churches independent of the Vatican. An underground Church loyal to the pope exists parallel to the state-sanctioned entity.

State-sanctioned bishops consecrated without Vatican approval are automatically excommunicated from the worldwide Catholic Church.

In 2007, Pope Benedict XVI wrote a landmark letter in which he said full reconciliation “cannot be accomplished overnight,” but added that “for the Church to live underground is not a normal situation.” The letter said there was only one Catholic Church in China and encouraged unity in their profession of faith, granting some validity to the Chinese Patriotic Catholic Association and permission for Catholics to participate in the official Church.

Currently, the Catholic population in the country is estimated to be about 12 million, with about half attending government-approved churches, and the other half attending “underground” ones.

On occasion, the two sides have mutually agreed on individual bishop appointments. However, current President Xi Jinping has made efforts to re-assert government control of religion in the country. Late last year, the Communist Party revised its “Regulations on Religious Affairs,” which was implemented Feb. 1, and it calls for greater “Sinicization” of Chinese Christians.

According to Zen, the proposed deal between the Vatican and Xi’s government would “cage” the members of the underground Church.

“The Communist government just wants the Church to surrender, because they want complete control, not only of the Catholic Church but all the religions,” the cardinal said last week. He also said he wasn’t completely against working with the regime: He proposed letting the Vatican nominate the bishops, with the government holding veto power.

Zen served as Bishop of Hong Kong from 2002-2009. The former British colony has religious freedom as part of the agreement with Britain leading up to the transfer of the territory to China.

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The open letter published Monday said the “moral integrity [of the seven illicitly ordained bishops] is questionable,” and added if they were to be recognized as “legitimate” then the faithful would be “plunged into confusion and pain.”

“We fully understand that the Holy See is eager to be able to evangelize in China more effectively. However, we are deeply worried that the deal would create damages that cannot be remedied,” the letter reads.

“The Communist Party in China, under the leadership of Xi Jinping, has repeatedly destroyed crosses and churches, and the Patriotic Association maintains its heavy-handed control over the Church. Religious persecution has never stopped. Xi has also made it clear that the Party will strengthen its control over religions,” the letter continues.

“So, there is no possibility that the Church can enjoy more freedom. In addition, the Communist Party has a long history of breaking promises,” it said.

The signatories said they are worried that the agreement would not only fail to guarantee the limited freedom desired by the Church, “but also damage the Church’s holiness, catholicity, and apostolicity, and deal a blow to the Church’s moral power.”

The letter acknowledges Pope Francis is “pained” by the suffering experienced by Christians in China but said the proposed agreement will not put an end to religious persecution, pointing to the new government regulations which “allows for stricter scrutiny over religions.”

“We cannot see any possibility that the coming agreement can result in the Chinese government stopping its persecution of the Church, and ceasing its violations of religious freedom,” the letter said.