Arguably, James Jarvis and Stephen Kumalo could be considered each other's foils. They certainly come from different backgrounds and from different walks of life, different races, classes, etc. Also, since Kumalo's son murdered Jarvis's son, they are certainly set up in opposition to each other. But the beautiful scene between the two in the rainstorm and the resulting generous acts done by Jarvis bring the two together in a very connected hope for the future of South Africa.
John Kumalo, actually, could serve as Msimangu's foil. He dismisses his faith, preferring what he perceives as a quest for power in his struggle against the apartheid, whereas Msimangu never loses sight of his faith, even though he is involved in the same struggle.