The Christian presence in China has a long but broken history, shrouded by the mystery of time. Legend has it that St. Thomas, one of the 12 apostles, travelled to China from India, converted some Chinese, and then returned to Meliapur, on the southeast coast of India, where he died. But no evidence has been found to substantiate this claim.

I was ordained a priest in 1951, the year His Holiness Pius XII experienced one of the greatest vexations and sadnesses of his pontificate – the breaking off of diplomatic relations with China, two years after the communists took power and expelled foreign Christians.

Foreseeing this, many missionaries left the country to avoid being incarcerated since they were considered agents of western imperialism. The Holy See did not want to abandon the Celestial Empire (China) and transferred the papal nuncio, Msgr. Antonio Riberi, to Taipei (Taiwan).

Many significant issues arose: If a deal was signed by the Vatican and China, what would happen to the 30 bishops already appointed by Rome but not accepted by Beijing? What would happen to the nunciature in Taiwan? Would there be two embassies of the Church in China – Taipei and Beijing?

Today, things seem to be different. The Holy See and China may be on the brink of a historic deal that could end decades of hostility and stalemate. The agreement would have unprecedented political, doctrinal and pastoral ramifications.

With Pope Francis the unpredictable is possible. Who could imagine that the leaders of the European Union would gather in the sanctuary of the Sistine Chapel, reserved for the conclaves for the election of a pope?

The stakes are so high that Cardinal Joseph Zen, the retired bishop of Hong Kong, has argued that such an accord would “betray Christ” and could signify a “surrender” to the communist regime. Cardinal Zen goes so far as to describe such an accord as perfidious for the faithful of the underground Church: “Unfortunately the Pope is surrounded by people not able to understand the Chinese culture.”

Intensive talks between the Vatican and the Chinese government have taken place for a year, both in Rome and Beijing. Pope Francis had hoped to seal a deal before the end of the Year of Mercy, a deadline that has now passed, but indications are that the completion of the negotiations may not be far away.

Cardinal John Tong, the current Bishop of Hong Kong, revealed in August that the Holy See and China had reached an initial agreement on the appointment of bishops, but no official details have emerged. In November, he said that “the concrete terms of the mutual accord have not been made public” – a hint that a deal has been made, but is being kept under wraps for now.

Last month, three new bishops were ordained with the approval of both the Holy See and China, a future sign of rapprochement. But to complicate matters, a bishop who has been excommunicated by Rome, Bishop Lei Shiyin of Leshan, recently took part in the ordination of the new Bishop of Chengdu, Joseph Tang Yuange.

At the heart of the reported deal is the question of authority over the appointment of the bishops in China. When the communists took power and the Holy See broke off relations with China in 1951, the regime established the state-controlled Chinese Catholic Patriotic Association (CCPA) which does not officially recognize papal authority. An underground Catholic Church, in communion with Rome, has existed since then, enduring severe persecution over the decades, with many of its bishops and priests jailed by the regime.

Yet, on the ground, the near distinction between the state and the underground churches is often blurred. Many bishops in the state-controlled CCPA, who are appointed by Beijing, are also recognized by Rome, and some Catholics in the underground Church have links with the CCPA. The idea that the two are entirely separate and do not mix is simplistic.

Bishops of the underground Church loyal to the Vatican often face imprisonment and persecution. Earlier this month, Cardinal John Tong announced that the Vatican and Beijing were nearing a deal on the appointment of bishops. He said Beijing would recognize the Pope’s right to veto any of the bishops they had selected.

On the other hand, Cardinal Zen said that a deal with Beijing could be a betrayal of loyal Catholics who must live out their faith in secret and who often suffer under the communist regime. He added: “The blood of the martyrs is the seed of new Christians, but if that blood is poisoned, how long will those new Christians last?”