Global Christianity by Gina A. Zurlo is a statistical guide to the world’s largest religion, organized by continent, tradition or movement, and country. It functions as a précis of World Christian Encyclopedia, 3^rd ed. (2019) and World Christian Database (2021), which she coedited with Todd M. Johnson. Zurlo is codirector, with Johnson, of the Center for the Study of Global Christianity at Gordon-Conwell Theological Seminary in South Hamilton, Massachusetts.

Between 1900 and 2020, which are the termini of the book’s statistics, Christianity grew from 558 million adherents to 2.5 billion. Despite the numerical growth, however, Christianity shrank slightly as a percentage of the world’s population, from 34% to 32% over the same time period. Moreover, the center of the world’s Christian population shifted from the global North (Europe and North America) to the global South (Asia, Africa, Latin America, and Oceania).

During that same time period, atheism and agnosticism grew from 0.2% to 12% of the global population, and Islam doubled from 12% to 24%. Demographers estimate that by 2050, Christians will constitute 35% of the world population and Muslims 29%. Clearly, Christians have their evangelistic work cut out for them.

As noted above, Zurlo organizes her statistical presentation by continent, tradition or movement, and country.

1. Continents. The six continents are Africa, Asia, Europe, Latin America, North America, and Oceania. While Europe and North America were the heart of Christendom in 1900, today, Africa has the largest number of Christians, with 667 million. It best illustrates the shift of the Christian population to the global South.

2. Traditions: Zurlo provides statistics on four Christian traditions: Catholic, Orthodox, Protestant, and Independent. The first three are well understood. Independent is a diverse category for groups and individuals “who do not self-identify with historic Protestant, Catholic, or Orthodox churches.” It includes African-initiated churches, Chinese house churches, nondenominational churches that are Pentecostal/Charismatic, as well as groups such as the Latter Day Saints, which are considered heretical or cultish by orthodox Christians.

We shouldn’t read Global Christianity merely to quench a thirst for data. We should read it to make better decisions about Christian mission in the modern world.

3. Movements: Evangelicalism and Pentecostalism are spiritual movements within the four traditions. Historically, Evangelicalism arose within 18^th-century European and North American Protestantism, and its theological emphases are found within both Protestant and Independent churches especially.

“Pentecostal/Charismatic Christianity is the fastest growing segment of World Christianity today,” Zurlo writes. The family resemblance in this movement centers on “the baptism of the Holy Spirit, the gifts of the Spirit, and the experiential nature of Christian faith.”

This movement’s annual growth rate between 1900 and 2000 was 6.3%, “four times as fast as both Christianity as a whole and the world’s population.” Its total population in 2020 is approximately 644 million. Today, the world’s largest Pentecostal/Charismatic population is Brazil, with 108 million.

4. Countries: One- to two-page country profiles — running alphabetically from Afghanistan to Zimbabwe — comprise the bulk of Global Christianity. Each profile includes a brief history of Christianity in that country, a bulleted list of “Facts to Consider,” graphs regarding religious trendlines between 1900 and 2020,  “Indicators and Demographic Data” about the country, and information on Bible translations, churches, missionaries, and gospel access. That last term refers to “the extent to which the Christian message has been spread, or the extent of awareness of Christianity, Christ, and the Christian message.”

In the Introduction to Global Christianity, Zurlo writes that the book answers “the most frequently asked questions about World Christianity”:

• How many Christians are in the world?
• Is Christianity growing or declining?
• What is Christian life like in other places around the world?
• Where are the most challenging places to be a Christian today?

Anyone reading the book will gain a better understanding of the state of global Christianity, its demographic trendlines, the cultural variety in which believers live out their faith, and the challenges many face in doing so.

The question the book does not answer, at least not at any length, is what readers are supposed to do with all this information. Zurlo writes, regarding the center she codirects, that its “data and publications help churches, mission agencies, and nongovernmental organizations (NGOs) to be more strategic, thoughtful, and sensitive to local contexts.” I think this points readers to an answer.

We shouldn’t read Global Christianity merely to quench a thirst for data. We should read it to make better decisions about Christian mission in the modern world, in terms of both evangelism and compassion. The book is informative, of course, but its information serves a larger missional purpose.

I highly recommend it to ministers, missionaries, church leaders, interested laypeople, and denominational and missions executives who desire the continued worldwide growth of the gospel.

Book Reviewed

Gina A. Zurlo, Global Christianity: A Guide to the World’s Largest Religion from Afghanistan to Zimbabwe (Grand Rapids, MI: Zondervan Academic, 2022).