A brief anecdote from my current research on the Midwest Indians:
In the 1820s the Episcopal Church set up a mission station and school for the Indians residing near Green Bay, Wisconsin. At the time the local Native American population consisted of a few Menominee communities, a colony of Stockbridge Indians (Munsees and Mahicans) from western New York, and (after 1832) a settlement of Oneida immigrants. The school, under the direction of Reverend Fish Cadle – really, you can't make these names up – offered instruction in the 3 Rs, grammar, and geography, but it attracted few students, and I get the impression that the church drew few converts. Part of the reason for this lies in the religious history of the eastern Wisconsin Indians: some of the Menominees were already Christian (Catholic), as were many of the Oneidas, and the Stockbridges had already founded their own Presbyterian church. A larger problems, I think, was the willingness of the missionary teachers to use corporal punishment on children not used to such treatment at home, and the difficulty the missionaries had feeding their students. Food was expensive in Green Bay and the Anglican missionary society was very parsimonious, so the few dozen pupils at the school were underfed and “sickly,” according to the report of a church inspector. This stood in contrast to the abundance that one could find at some local Indians' tables: when ministers visited local Oneida families in 1834 their hosts treated them to “pork & beans...chicken pies, squashes, potatoes, peas & rice pudding.” I do not get the impression that the missionaries learned very much from this experience, but there are clear messages for modern readers less invested in Rev. Cadle's ideology: the Indians of eastern Wisconsin were not “blank-slate” pagans awaiting the Episcopalian Gospel, and neither were they starving savages – indeed, they could better feed their guests than the missionaries could provide for their students. (David R.M. Beck, Siege and Survival: History of the Menominee Indians (2002), 125-127; Jackson Kemper, "Journal of an Episcopalian Missionary's Tour to Green Bay, 1834," Collections of the State Historical Society of Wisconsin 14 (1898): 394-449, quotes pp. 426, 433.)
Perhaps, in the manner of many missionaries, Cadle and his co-workers believed they were offering students more important treasures than mere material sustenance, but it's hard to appreciate geography or Christian theology on an empty stomach. This was a lesson that did not escape other missionaries: Franciscans in New Mexico and Texas often drew in potential converts by accumulating large food supplies, or at least grain crops and herds of beef cattle, in their missions, and commenters on the Baptist mission to the Kansas Shawnees opined that many families had placed their children with the boarding school in order to feed them, which (given the hardships the Shawnees experienced as a result of Removal) may well have been the case. If one believes that one cannot turn Indians into Christians without completely isolating them from their community and old lifeways, one has to make some effort to feed and shelter the converts, unless one wants them to become dead converts.* “Grub first, then morals,” as the playwright said. (Andrew Knaut, The Pueblo Revolt of 1680 (1995); Juliana Barr, Peace Came in the Form of a Woman (2007); Kevin Abing, "A Holy Battleground: Methodist, Baptist, & Quaker Missionaries among Shawnee Indians," Kansas History 21 (1998): 118-37.)
* That missions and boarding schools often had very high rates of epidemic disease was something missionaries deplored but attributed to God's will. Until the nineteenth century missionaries' medicinal toolkit was generally no more effective than that of their Native American converts, a point Andrew Knaut makes in his book on the Pueblo Revolt.