Unity is only possible when Christians get Jesus and their mission right. The document outlines two key points: 1) Getting Jesus right means not dividing over human leaders like Paul or Apollos, but focusing on Christ. 2) Getting the mission right means preaching the gospel of Christ's death and resurrection, not relying on human wisdom, as that is what brings unity by breaking down walls between people. The overall message is that unity among Christians requires focusing on Jesus and the mission to spread the gospel.