Oneness Pentecostalism is a rapidly-growing theological movement that challenges the historic Trinitarian explanation of the Bible. Oneness Pentecostals claim that Jesus Christ is God himself Incarnate. On standard models of Oneness Christology, this means that Jesus and the Father are not numerically distinct subjects: the subject who is the Father is also the subject who is Jesus Christ. One way to test a theological system is to see what claims in the New Testament would be surprising if it were true. An analysis of Revelation 3:21 shows that there are four contextual truths for which any theological explanation of the verse must account and that these truths are surprising if a standard Oneness Christology is true. In order to account for these contextual truths, Oneness Christology must be modified to allow for Jesus and the Father, at some level, to be numerically distinct subjects. However, even a modified Oneness Christology fails to account for Revelation 3:21 as straightforwardly as two alternative explanations.