Witnessing the largest-ever Christian gathering during his 1973 Seoul Crusade, Billy Graham posed for photos with his leadership team in front of the audience on Yoido Island.

It was a special event that Graham wanted to share with his staff, but it was also an extraordinary moment in the history of Christianity in Asia. On the tiny river island in Seoul, Graham saw the future of a continent and predicted that Korea could be a base for preaching the gospel throughout Asia.

More than 30 years later, it seems Graham was right.

Since the birth of the Korean church, evangelism has been one of its defining characteristics. In 1907, a major revival in Pyongyang coincided with the creation of the autonomous Presbyterian Church of Korea—after only 23 years of Protestant missionary work. The year also marked the ordination of the first Korean missionary.

In following years, the Korean church sent missionaries to Siberia, Manchuria, and Hawaii. Samuel Kang, a missiologist and former missionary, says the Korean church sent 157 missionaries between 1907 and 1937.

The church fought for survival during Japanese occupation and the Korean War, but the Koreans' evangelistic zeal remained fertile soil for the modern missions movement that grew out of Western evangelistic efforts and a student revival.

David Lee was one of the leaders of the '60s student revivals. He says, "We'd have 500 to 600 students gather for several hours of prayer, and we would pray for missions." Revival, Lee says, leads directly to evangelism.

In 1973, about 3.2 million people attended the Billy Graham Crusade, including 1 million on the final day of the crusade—the largest recorded Christian gathering up to that time. The entire country of South Korea had roughly ...