What is Christianity?. Douglas Jacobsen

humankind with different visions of the world as it is and could be, they offer different pathways to and definitions of salvation, and they advocate different ideals and values. Christianity is a powerful and inspiring religion, but it is not the simple religion that Harnack described.

      In contrast to Harnack’s idealistic portrayal, this book offers a more empirical examination of what Christians have believed, how they have acted, how they have organized themselves, how they have spread their message around the world, and what challenges they are facing today. There is no intention to either criticize or praise the movement; the only goal is fair and accurate description. That said, this book is more than a mere recital of facts and numbers quantifying Christianity from the outside. It also looks at Christianity from the inside, trying to explain Christianity’s spiritual appeal and why so many people around the globe have embraced it.

One obvious fact about Christianity is that it is a far different movement today than it was a century ago when Harnack gave his university lectures. In 1900, two-thirds of the world’s Christians still lived in Europe. Today, only a quarter of the world’s Christians reside in Europe and about 10 percent live in North America. The rest, two-thirds of all the Christians in the world, live in the Global South (Africa, Asia, and Latin America). The internal composition of Christianity has also been transformed. In 1900, three major Christian traditions (Eastern Orthodoxy, Roman Catholicism, and Protestantism) dominated the Christian movement. Now there are four major traditions. The addition is Pentecostalism, and this new tradition, which currently attracts one out of every five Christians globally, has dramatically altered the Christian landscape.³ Simultaneously, the terrain of global politics has been fundamentally reordered. In 1900, half the world’s people were ruled by European colonial governments. Today those former colonies are independent nations, and the Christians who live in them are fully independent of Western Christian control. Christianity is no longer a European religion with a periphery everywhere else; Christianity has become a postcolonial, global faith with many different centers.

This book describes Christianity in eight chapters. Chapter 1 explains how the movement got started, and how within 500 years a small group of followers of Jesus grew into a religion that had a membership that spread across a massive region of the world, ranging from Ireland in the northwest to the southern tip of the Indian subcontinent. Chapter 1 also traces how Christianity changed from a loosely structured and fluid movement into a religion comprised of separately organized and distinct Christian traditions. Today, Christianity is housed in four major traditions – Eastern Orthodoxy, Catholicism, Protestantism, and Pentecostalism – and these four traditions account for about 97 percent of all the Christians in the world. Chapters 2 through 5 explain each of these traditions in turn.

      The remainder of the book deals with the characteristics of Christianity as a whole. Chapter 6 describes Christianity’s recent expansion around the world and the changing attitudes of Christians in both the Global North (Europe and North America) and the Global South (Africa, Asia, Latin America, and Oceania). Chapter 7 describes the dramatically different experiences of Christians around the world today. Some Christians are persecuted; others are persecutors. Some Christians are wealthy; many are poor. In some regions Christianity is growing; elsewhere it is in decline. Despite all of these differences, most Christians continue to see themselves as members of one religion. Chapter 8 explores this sense of Christian connectedness, describing what most Christians hold in common while also reflecting on a variety of religious challenges that Christianity is currently facing as a global movement. The Conclusion returns to the main question of the book and argues that Christianity today is what it has been throughout its long history: a religion that is still in the process of forming and reforming itself in response to changing circumstances and in light of its memory of Jesus.

      Notes

      1 1 Adolph Harnack, What Is Christianity? translated by Thomas Bailey Saunders (New York: Harper and Row, 1957), p. 112. Harnack’s lectures were originally published in German in 1900 under the title Das Wesen des Christentums, which could literally be translated as “The Essence of Christianity.” They were published in English in 1902 using the present title.

      2 2 Professors of Germany, “To the Civilized World,” The North American Review 210:756 (August 1919), pp. 284–287, https://www.jstor.org/stable/pdf/25122278.pdf?acceptTC=true (accessed September 8, 2020).

      3 3 The demographic information included in this book represents the author’s best estimates based on a variety of sources. The most complete and reliable source of information is the World Christian Database (https://www.worldchristiandatabase.org) and it has been consulted frequently. The numbers used here are not, however, taken directly from the WCD. They have sometimes been adjusted based on other information (from, for example, the United Nations or different national census figures) and the reporting categories differ from those of the WCD. Numbers in this book have been consistently rounded off to reflect that they are indeed estimates and not actual headcounts of Christians in different traditions, nations, or regions of the world. The goal has been to include all people who self-identify as Christian wherever they may live and whatever they may believe.

1 Christian Beginnings

      The religion called Christianity did not spring into existence with its identity already fully developed and finalized. At first, Christians did not even know what to call themselves. The New Testament book of Acts refers to them simply as “followers of the Way” and infers that the term “Christians” was first used by others, possibly as a derogatory means of distinguishing disciples of Christ from other kinds of Jews. What seems clear is that Jesus had a powerful impact on his closest friends and associates and that those allies were able to communicate their enthusiasm about Jesus to others. In a sense, Christianity began as something like a fan club for Jesus. This is not meant as criticism, but merely as description. A fan club is held together by its devotion to a person, not by the ideas or ideals that demarcate its identity. Earliest Christianity was indeed something like a fan club: it was a movement of devotion to Jesus long before it developed a clear and distinct sense of its own religious identity.

      Religious identity is a group phenomenon. Everyone has their own spiritual sense of who they are, but religions are bigger than any one individual. A religion is a community that a person joins, or is born into, that connects participants with the divine (or more generally with “the transcendent”) and provides guidance for the journey of life. Religions are not meant to be easily modified to conform to one’s wishes; indeed, few people want their religion to be pliable and undemanding. Religions are instead expected to provide a standard to which individuals conform, an ideal worthy of utmost human effort. People change their lives to fit their religion, not the other way around.

Religious identity consists of the beliefs, actions, values, personality traits, affectivities, and organizational structures that a religious community champions and shares with others. This does not mean that every member of the group agrees about everything. No group of people is ever that uniform. What it does mean is that members of the group hold enough things more-or-less in common that they feel a sense of belonging together. They recognize each other as family. They understand how people in the group think and know how members of the group feel about themselves, about others, and about the