Amid the speculation that the new Hong Kong cardinal will bring new progress in the diplomatic relationship between China and Vatican, the cardinal challenges China’s official Catholic Church.

On Saturday, Cardinal Joseph Zen was interviewed by the leading Hong Kong radio station RTHK. As an outspoken religious leader who advocates religious freedom and democracy, Zen has challenged the official Catholic Church in China, saying "China should be able to see that all Catholic churches around the world are led by bishops. It cannot be led by another group," according to the Associated Press (AP).

Since 1951, the tie between the Vatican and China was broken since atheist Communists took power. Catholics are not allowed to join churches that are loyal to the Vatican. This group of believers that refused to give up their affiliation with the Vatican, they will gather dependently, so-called underground churches. They are often subjected to harassment and persecution.

One of the very big issues concerning Sino-Vatican relationship will be the appointment of bishops. Under the existing religious law in China, the Chinese government appoints its own bishop for each government-controlled church for each province.

Zen said on Saturday it was "unacceptable" for the official Patriotic Catholic Association to lead Chinese Catholics.

Through the elevation of Zen to Vatican cardinal, Zen wishes to perform as the bridge between the Vatican and China, so that both sides can understand each other better. He has also emphasized that for the Sino-Vatican relationship to be recovered, religious freedom and human rights must be guaranteed by Beijing.

"There would have to be some changes first on China’s part," said Zen. "Is there a promise that these practices could be corrected?"

So far, China has not responded to Zen’s comments. However, according to AP, the Patriotic Catholic Church made clear its distrust of Zen earlier this month, when one of its leaders questioned the Vatican’s decision to appoint Zen as cardinal and said it could be an attempt to topple the Communist Party.

Despite the uncertainty faced by Chinese Catholics, Zen urged Chinese Catholics to be patient, helping to build a harmonious society and working for the "maturity" of the nation, a Vatican-affiliated newspaper Zenit reported on Thursday.

"Winter has passed, and spring has come," he said. "The seeds you have sown with tears will bear fruit very soon."