For a book that discusses religion to such a great extent, it's interesting that we should see two ministers who couldn't be more different. Rev. Merrill is quiet and dignified; Rev. Wiggin is kind of brash and hokey. Rev. Merrill seems to be a man of thought while Rev. Wiggin is a man of action. Rev. Merrill doubts his faith (well, until the very end of the novel, at least) while Rev. Wiggin has religious conviction to spare. We learn more about both of these men by contrasting and comparing them with one another, and that's what makes them each other's foils.