A.S. Geyser was professor of New Testament at the University of Pretoria from 1946 to 1961, when he accepted an appointment at the University of the Witwatersrand. He was one of the most active and outspoken critics of apartheid and played a leading role in the establishment of the Christian Institute and the appointment of Beyers Naude as the first director of the Institute. However, Geyser received very little attention either in church history or in the history of South Africa. (...) This contribution, presented as the Third A.S. Geyser Commemorative Lecture at the University of Pretoria, reflects on Geyser’s ecclesiology. It is quite remarkable that Geyser chose ecclesiology as point of entry into the discourse on apartheid. He engaged in fundamental theological criticism of segregation in church and state based on his understanding of the unity of the church in Christ and a humanity unified under the kingship of Christ. (shrink)