The landscape of the West—the plains, valleys, deserts, mountains, canyons—and its effect upon the people who inhabit it provide one of the themes in any Zane Grey Western. Riders of the Purple Sage is one of seven Grey novels set in Utah. The purple sage of the title covers a wild upland waste where several breakneck rides occur during the course of the novel. Grey’s descriptions of the natural features of the Western terrain are frequent, lengthy, and vivid. Even critics who fault his plotting, characterization, and occasional clumsiness of style agree that his descriptions of the West are masterful.

A second recurrent theme is the blindness of organized religion to the complexity, and occasional ambiguity, of moral choices. Grey does not limit his negative portrayal of religious groups to the Mormons. He is understandably more oblique in his criticism of other Christian communities, since much of his middle-American audience would belong to these very communities. Yet it is sectarian narrowmindedness that sends the protagonist of The Rainbow Trail (1915), the sequel to Riders of the Purple Sage, out west at the beginning of that novel. Reverend John Shefford leaves Quincy, Illinois, after breaking with his congregation. In The Vanishing American (1925), Grey did offend some religious groups by portraying the head missionary on an Indian reservation as a criminal who hides behind the Bible (which he calls the “Old Book”). Grey also writes of the absurdity of the idea that the Indians could be converted to Christianity in a short time. A major theme in Riders of the Purple Sage is that when the heart is in conflict with religious dogma, one should follow the heart.