Folk religion, as the basis of the religious landscape in traditional China, is a highly syncretic system which includes elements from Buddhism, Daoism, and other traditional religious beliefs. Due to the shortcomings of denomination-based measurement, most previous social surveys have documented a very low percentage of folk religion adherents in China, and found almost no overlapping among religious beliefs. This study offers a quantitative portrait of the popularity, the diffuseness, and the diversity of Chinese folk religion. With the improved instruments in the 2018 China Family Panel Studies, we first observe that nearly 50% of respondents claim to have multiple (two or even more than three) religious beliefs and the believers of folk religion account for about 70% of the population. By using latent class analysis, this article explores the pattern of inter-belief mixing and identifies four typical classes of religious believers: “non-believers and single-belief believers”, “believers of geomancy”, “believers of diffused Buddhism and Daoism”, and “believers embracing all beliefs”. Finally, we find that the degree of commitment varies across these religious classes. Believers of folk religion are found to be less committed than believers of Western institutional religions, but as committed as believers of Eastern institutional religions.