Every Sunday morning, Mr Olsen Zheng puts on his smartest outfit and makes his way to a movie theatre in the heart of Beijing.
The hall is packed to the brim, but it is not a box office hit that has drawn the crowds. Rather, it is an underground church service that has the theatre so full that people are sitting on the floor.
The cinema doubles up as a church for some 200 Christians on weekends, and is one of the thousands of unregistered churches across China that are attracting a growing number of young Chinese believers, like Mr Zheng, 28.
"I became a Christian in university after I visited a church out of curiosity and boredom," he said. "But the message of love and hope appealed to me. It made me stronger and made life more meaningful."
According to a recent survey by Renmin University, religious Chinese are getting younger, with more than half of them under 60 years old. China's five official religions are Buddhism, Taoism, Catholicism, Protestantism and Islam.
This finding echoes a study in 2007 by East China Normal University that found the proportion of religious believers in China is skewed towards the young, with 62 per cent aged between 16 to 39. In the previous decade, most were in their 40s or older, while prior to 1996, it was the above 60s who made up the majority.
In the latest survey, both Islam and Catholicism were found to have the highest proportion of believers under the age of 30 - at 22 per cent - while Buddhism had the highest percentage of followers above 60.
While China's Constitution guarantees religious freedom, the issue is a sensitive one for the officially atheist Communist Party, which heavily regulates religious activities and is cautious of institutions it sees as a challenge to its rule.
It might have become more wary after a prediction last year by Purdue University's religion expert Yang Fenggang, who said China could be home to the world's largest number of Christians, with 247 million believers by 2030 - almost three times the Communist Party's 88 million members.
State-run Global Times newspaper, however, questioned the forecast, citing an unnamed official as saying the estimate is "unscientific and obviously an exaggeration".
Experts say that, almost 40 years after the end of the Cultural Revolution, religion's growing popularity, especially among its young people, has become a "defining phenomena of Chinese social life".
"People born after the mid-1970s were educated after the Cultural Revolution, and did not experience its religious repressions," said Dr Robert Weller of Boston University's Institute on Culture, Religion and World Affairs. "They may have a more open-minded attitude to religion and worry less about joining in."
Mr Liang Xingyang, a Taoist priest from Shaanxi province, said more young people have reached out to him. Of the more than 160 disciples he has, the majority are between 20 and 40 years old.
"People have fewer material worries. It's not surprising that young people are now turning their attention to their spiritual well-being.
"The resurgence of interest in traditional Chinese culture has also helped spur interest in Taoism, while the Internet has made it easier to get information," he added.
Xinjiang native Hao Liya, 22, is one such convert. She was ordained as a Taoist priest this year .
But Ms Hao, who has an engineering degree, faces objections from her parents, who are not religious. "They don't understand why I want to make it a 'career'... I think their resistance is due to their lack of understanding of Taoism," she said.
As religion makes a comeback, there are concerns that two of China's fastest growing faiths - Christianity and Islam - could lead to rising tensions with the state.
The proportion of Christians is expected to rise to 5.4 per cent in 2050, from 5.1 per cent in 2010, while that of Muslims is projected to hit 2.7 per cent, from 1.8 per cent, said a Pew Research Centre study.
Already, there have been clashes in Xinjiang, home to a majority Muslim Uighur population, where the authorities have been accused of religious oppression. Christians in Zhejiang province have also alleged that the government demolished their churches.
Dr Lionel Jensen, a professor of East Asian language and culture at the University of Notre Dame, said Beijing considers the accelerated growth in the scope and diversity of religious practice "ominous".
"As religious enthusiasms become more prominent, there is more political attention... Religious tensions in China under the Xi Jinping regime are the most elevated I have ever seen," he added.
Prof Yang said Beijing's handling of the country's rising religiousness has been "very poor... and antagonises masses of believers".
But Dr Weller noted that the situation varies widely, with local governments adopting different policies. Most religious Chinese, even Muslims and Christians, do not face these tensions, he noted.
The exceptions are a few "hardcore groups" that bristle at any government interference, primarily a small but visible set of Muslim and Christian groups, he said. The other exception is Xinjiang, where policy tends to be more rigid.
"So I don't think it's right to say that these faiths are in tension with the government; rather just certain small groups are," Dr Weller said.
This article was first published on Aug 01, 2015.
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