An additional perspective comes from Alan Paton who was a very religous man and felt that religion could bring all men together. (See the foreward and introduction in the book.)
The author's point-of-view regarding the unifying force of religion can be seen in the relationship between Kumalo and Jarvis. While very strict racial lines are drawn between the two men, the church helps bring them together for a common purpose--the native people living on the land.
The voice could be seen as Kumalo--his deeds are yet to be proven. (As seen in Kumalo's relationship with his son, his wife, and un-born grandchild.)