On June 9, the Pew Research Center released its newest report titled "How the Global Religious Landscape Changed From 2010 to 2020," introducing a revised approach for measuring religious affiliation in China.
According to the report, 1.3 billion people in China—90% of the population—identified as religiously unaffiliated in 2020, making China the country with the largest unaffiliated population in the world. Meanwhile, China's Christian population remained outside the world's ten largest.
The report revised its method of estimating religious composition in China. In past research, Pew had used "custom estimates" for China to adjust for limitations in local surveys, which often fail to capture people's religious identity fully. This time, however, the report adopted a standardized measurement of "zongjiao" identity—formal religious affiliation—because it offers the greatest comparability with other countries and is more consistent over time within China.
Pew's earlier estimates for China (first published in 2012) were based on a broader set of indicators from the 2007 Spiritual Life Study of Chinese Residents, including self-identification, belief, and practice. Using that framework, Pew initially classified 52% of the Chinese population as religiously unaffiliated. In contrast, the revised method relies solely on one question—"What is your religion?"—using the Chinese term "zongjiao." Based on this narrower self-identification, Pew now estimates that 87% of Chinese people had no formal religious affiliation in 2010.
The report acknowledges limitations in using "zongjiao" identity as the sole measurement of religious affiliation in China. Pew researchers note that this metric likely omits individuals who hold religious beliefs or engage in religious activities but do not consider themselves formally affiliated with a religion. Scholars also point out that such surveys may undercount Christians in particular, especially those worshipping in unregistered churches, due to reluctance to participate in surveys or disclose religious identity to interviewers.
However, the previously used custom estimation approach had drawbacks, particularly in terms of comparability with data from other countries. It also lacked clarity on whether underreporting of Christian identity was increasing, decreasing, or remaining stable over time. The new approach, by focusing on "zongjiao" affiliation, enables Pew to assess religious change within China using the same metrics applied globally.
Using this new approach, Pew estimates that China had the largest unaffiliated population globally in both 2010 and 2020, with 1.3 billion unaffiliated people in 2020, amounting to 90% of the population. Only 10% of China's population identified with a religion, the lowest proportion of any country in the study. Because of China's vast population, this new methodology significantly raises the global estimate of the religiously unaffiliated.
The report points out that despite media reports during the 2010s suggesting that China was on track to become the country with the world's largest Christian population, the survey data show that Christians in China remain outside the 10 largest in the world. Based on self-identified religious affiliation, Pew estimates that there were about 25 million Christians in China in 2020. The United States remains the country with the largest Christian population, with Christians making up 64% of its population, about one-tenth of all Christians worldwide.
Globally, most religious groups grew between 2010 and 2020 as the world population increased. Christians remain the world's largest religious group, but their growth has not kept pace with the global population. While the Christian population increased by 122 million to reach 2.3 billion, its share of the global population declined by 1.8 percentage points to 28.8%.
Muslims were the fastest-growing group, adding 347 million adherents—more than all other religious groups combined—and rising to 25.6% of the world population. The religiously unaffiliated also grew, increasing by 270 million to 1.9 billion, now making up 24.2% of the global population, the third-largest group globally, after Christians and Muslims.
Christians are the most geographically dispersed religious group. As of 2020, 31% of the world's Christians lived in sub-Saharan Africa, followed by 24% in Latin America and the Caribbean and 22% in Europe. This marks a sharp shift from the early 20th century, when two-thirds of Christians lived in Europe and just one percent in sub-Saharan Africa. Africa's high fertility and Europe's religious disaffiliation explain the reversal.
The report identifies 41 countries where the Christian share of the population changed by at least five percentage points between 2010 and 2020. In all but one—Mozambique—the proportion declined.
The changes in global religious populations are driven by two main forces: natural growth (births minus deaths) and religious switching. Disaffiliation, especially among Christians, has been a major driver of the unaffiliated population's rise.
In its analysis of adults aged 18 to 54 across 117 countries and territories, Pew found that for every one adult raised unaffiliated who became religious, 3.2 adults raised religious left their faith. Christianity experienced the largest net loss from switching: for every one convert to Christianity, 3.1 people left the faith. Most of them became unaffiliated, while a smaller number converted to other religions.
