Worshippers pray during a mass at the Liuhe Catholic Church on the outskirts of Qingxu county
Worshippers pray during a mass in the morning at the Liuhe Catholic Church in Liuhe village on the outskirts of Qingxu county, northern China's Shanxi province, September 11, 2011. Liuhe is one of the largest parishes in mainland China, where about 90% of the population are Catholics. REUTERS

BEIJING -- Christianity in China is booming despite the government's rigorous attempts to control religious practice. Yet in the past 15 years, Protestantism has grown at more than twice the rate of Catholicism, a fact that may reveal as much about the government's hold on the churches as it does about the spiritual vitality of China.

A precise headcount of Christians in China proves elusive. Too much of the country's religious observance operates under the radar, and there are also obstacles of definition. Yet the existing, albeit imperfect, estimates demonstrate that while Christianity as a whole is growing, Protestantism is growing faster by far.

By the government's own numbers, Protestants have increased by more than 60 percent in the last 15 years, numbering 23 million as of 2010. Within the same period, the number of Catholics grew by more than 25 percent, with the official headcount hovering around 5.7 million.

These numbers are certainly low; the Chinese government counts only those who worship in the officially registered churches, and most Christians in China worship in unofficial house or underground churches.

But the trend holds even in studies factoring those who worship outside the state-approved churches. According to a December 2011 report by the Pew Forum on Religion and Public Life, Protestants worshipping in both the official and unofficial churches were estimated at 58 million, while Catholics numbered 9 million in total. Other, more high-end estimates of Catholics reach around 12 million.

The primary reason for this growth disparity is generally agreed upon by experts both within and outside of the Church: It's simply tougher to become Catholic.

Lucia Cheung, the China editor of the Union of Catholic Asian News, explained that the process of Catholic conversion usually takes a year and a half of study, though the process is accelerated in some places in China. Catholics [are] more strict in accepting a new member, she said. It is not like the Protestants. Some of them just need to say, 'I believe,' and they're regarded as a Protestant.

As China has urbanized and liberalized, many people have found the much-lauded attainments of wealth or status unfulfilling. Foreign religious workers often reference China's exceptional spiritual curiosity. And unlike in the West, large portions of the population have no previous contextual knowledge of religion whatsoever.

Protestantism's simplicity has fueled its spread -- but China's Christian population is increasingly urban, educated and sophisticated. Such converts pose hard questions to their spiritual leaders, and they want thoughtful answers.

The Catholic Church is, at least theoretically, in a better position to answer tough theological questions. Priests-in-training generally study around seven years, preparing not only to preach but also to administer sacraments. Their Protestant counterparts, whose responsibilities are simpler and less ceremonial, typically graduate from Bible school in fewer than four years. Many Protestant pastors have one year or less of formal training.

In China, educational opportunities are sparse for both Catholics and Protestants. There are only 12 official Catholic seminaries and fewer than 25 Protestant seminaries in all of China. And because Catholics spend more time in study, the official Catholic seminaries graduate fewer than 20 each year, while Protestant schools graduate up to 200.

While priests can get training outside the state-run schools, either abroad or in unregistered Chinese-Catholic seminaries, they face significant hurdles because they must operate covertly. Even counting those trained in so-called underground seminaries, there are only about 3,500 priests for China's entire Catholic population. One could justifiably suspect that this leadership deficit contributes to Catholicism's slower growth.

Another factor may be that Catholicism is often perceived to be more politically loaded within China, where politics often remain a decisive factor in career success.

Unlike Protestantism, Catholicism is centralized and organized in structure, which makes the government uncomfortable. Moreover, the Catholic Church has long been at odds with China's communist leadership. As early as 1946, Chinese Catholics were forbidden to support Maoist troops under the direction of the vehemently anti-communist Archbishop Antonio Riberi. To this day, Catholic leaders -- particularly cardinals in Hong Kong and Taiwan -- have been outspoken about the need for democracy in China. Accordingly, there have been no formal relations between the Chinese government and the Vatican for 60 years.

So it comes as no surprise that the Chinese government remains wary about Catholicism, which it considers a distinct religion, defining it alongside Christianity among the government's five officially recognized faiths. Referencing Catholicism's role in Poland's regime change, Deng Xiaoping once warned of the Polish disease-- what Human Rights Watch's Mickey Spiegel defines as the alliance of religion and independent social forces, which in Poland empowered the trade union Solidarity in opposing the Communist-led government. And even informal relations between Beijing and the Holy See have been strained, particularly as the Chinese government has appointed bishops not approved by the Vatican. The Catholic Church has also appointed bishops unrecognized by China's official system, about 40 in total.

Given this ongoing conflict between church and state, God-seekers may find Protestantism more politically opportune. To be sure, the Protestant population has also faced persecution. But many observers say Christian oppression has been concentrated more toward Catholics than Protestants in recent years.

Yet despite gaining fewer converts, Catholicism benefits from a long history and tradition, as well as an organized structure unparalleled among Protestants in China or elsewhere. Undeniably, the Church's consistent message has bought it credibility. All these factors ensure Catholicism's continued relevance to China's political, economic --and particularly, spiritual -- development.

Jillian Melchior is a foreign correspondent writing about China.