This book investigates the Mission of the Reformed Church in America sent to Arabia in 1889 to preach the Gospel, and which operated in the Persian Gulf until 1973. It also explores the various cultural encounters between missionaries and Muslims, and discusses conversion and the place of Islam in the Protestant eschatology. It maintains that John G. Lansing from the New Brunswick Theological Seminary, New Jersey, who founded the Arabian Mission, deliberately dedicated the Mission to “direct Muslim evangelism”. In terms of premillennialism, Lansing “moved” Islam into the very centre of the theological discourse, and presented the evangelization of Muslims as critical for Christ’s Second Coming. This made the Arabian Mission unique among the American Protestant Missions, and placed the Church and missionaries between religious pluralism and the obligations of the Great Commission.