It was startling for me to learn that Lewis, who published Elmer Gantry in 1927, had himself once pledged to become a Christian missionary, preferably in Africa, in 1902-1903 while he was a teenager studying at Oberlin Academy, a then secondary-school department of the eponymous Ohio college.  That kind of aspiration was far from the mind of Lewis’s Gantry, originally a traveling salesman for a farm implement company, who, after switching to preaching and securing a pulpit of his own, was, Lewis wrote, “like the new general manager of a factory as he bustled for the first time through the Wellspring Methodist Church, Zenith, and his first comment was ‘The plant’s run down — have to buck it up.’” 
The Gantry generation operated in ways starkly different from Andover’s — there wasn’t any money in it back in the nineteenth century, at least not for individual preachers. But in 1939, historian Colin Brummitt Goodykoontz drew a direct line between the beliefs of Fundamentalist Christians — the literal interpretation of the Bible and the imminence of the Second Coming, for example — and the efforts of earlier missionaries. Making his case in Home Missions on the American Frontier, he concluded that “Puritanic theological concepts and practices were set up and cherished in the West through home missions” and that it was “not by chance that the South and Middle West have been the strongholds of fundamentalism and the chief centers of such traces of Puritanism as remain in this country.”  Goodykoontz, a member of the First Congregational Church of Boulder, Colorado, where he taught at the University of Boulder for many years, wasn’t unhappy about this outcome, however; he was full of praise for it. “They toiled obscurely and laid down their lives freely in order that others might live more abundantly,” he wrote. “They were spiritual leaders who stood for idealism in the midst of materialism. They believed that righteousness exalted a nation and that sin is a reproach to any people.” 
Goodykoontz ended his book by quoting Theodore Roosevelt, who had said much the same thing in 1902, while speaking at Carnegie Hall at the Centennial Meeting of the Board of Home Missions of the Presbyterian Church: “It is because of the spirit that underlies the missionary work, that the pioneers are prevented from sinking seriously near the level of the savagery against which they contend. Without it the conquest of this continent would have had little but an animal side. Without it the pioneers’ fierce and rude virtue and somber faults would have been left unlit by the flame of pure and loving aspiration. Without it the life of this country would have been a life of inconceivably hard and barren materialism.” 
Leaving aside the fallacies Roosevelt uttered on the occasion, it’s notable that he failed to mention the inconceivably hard lives led by most missionaries. Together with their families, both at home and abroad, they suffered unrelenting disease, death, sometimes violence, and, unless they were superhuman, grave doubts about whether what they were doing was worth all the sacrifices. Granted, doubt doesn’t marry well with dogma, and it seldom manifested itself in missionaries’ mass-produced writings, especially in those posthumously ghost-written and edited by others, but the inner dialogue of fictional missionaries regularly display it.
In Brian Moore's 1985 novel Black Robe, a depiction of Jesuits working among Huron, Iroquois, and Algonquin people in seventeenth-century Canada, Father Laforgue wrestled with theological uncertainty as he watched an Indian friend die. Thinking “of God’s mercy denied him,” he said to himself, “I must not dwell on these things. It is the devil who puts such thoughts in my head.” “But is it the devil?" he wondered. "What has happened to me? Why do I no longer pray?”  Likewise, the twentieth-century missionary in Paul Bowles’s short story “Pastor Dowe at Tacaté” fell into a deep despair while experiencing “the sensation of having communicated absolutely nothing” to the Mexican Indians he was trying to convert.  He had a little portable phonograph on which he played “Crazy Rhythm” for them over and over again. It had become an integral part of his weekly service, because the Indians had insisted upon it. He reasoned that they would “learn to want God” just as much as they wanted music.  But it didn’t happen. “Everything I say is transformed on the way to them into something else,” he said to himself. It was “a manner of thinking that Pastor Dowe had always taken pains to avoid.”  He tried to motivate himself to carry on: “‘God is always with me,’ . . . but the formula had no effect.” 
1. Sinclair Lewis, Arrowsmith, Elmer Gantry, Dodsworth (New York: The Library of America, 2002), 542.
2. Lewis, 1318,
3. Lewis, 791.
4. Colin Brummitt Goodykoontz, Home Missions on the American Frontier, With Particular Reference to the American Home Missionary Society (Caldwell, Idaho: The Caxton Printers, Ltd., 1939), 425-426.
5. Goodykoontz, 426.
6. Goodykoontz, 426-427. For the complete speech, see https://www.presidency.ucsb.edu/documents/remarks-the-centennial-meeting-the-board-home-missions-the-presbyterian-church-carnegie. Retrieved Apr. 22, 2021.
7. Brian Moore, Black Robe (New York: E.P. Dutton, 1985), 00.
8. Paul Bowles, The Stories of Paul Bowles (New York: Ecco, 2001), 107. "Pastor Dowe at Tacaté" originally appeared in Mademoiselle, February 1949.
9. Bowles, 115.
10. Bowles, 116.
11. Bowles, 120.