Ohiyesa (who took the Euro American name Charles A. Eastman) grew up as a Dakota before the White takeover of the Great Plains.
His father, sensing the inevitability of White expansion, urged him to learn the White culture's knowledge and ways. Eastman received a classic liberal arts education and became a medical doctor, returning to serve on the newly formed Reservations. He provided care to the victims of the Wounded Knee massacre on the Pine Ridge Reservation in 1890.
Because he had grown up in authentic Dakota culture and had gained literacy and understanding of the White world, he was able to share insight into Native culture and spirituality, while admitting that it was so intuitive as to be undone by written concepts. His father had converted to Christianity and Ohiyesa took the name Charles after being baptized. The family belonged to the Presbyterian Church, and one brother went on to become a Presbyterian minister.
Dr. Eastman's "Soul of the Indian" (1911) is still on University reading lists. It presents a caution about the damage done to Christian witness by denominationalism, propositional religion, and cultural trappings that obscure the attractive mystery of God:
The first missionaries, good men imbued with the narrowness of their age, branded us as pagans and devil-worshipers, and demanded of us that we abjure our false gods before bowing the knee at their sacred altar. They even told us that we were eternally lost, unless we adopted a tangible symbol and professed a particular form of their hydra-headed faith.
We of the twentieth century know better! We know that all religious aspiration, all sincere worship, can have but one source and one goal. We know that the God of the lettered and the unlettered, of the Greek and the barbarian, is after all the same God; and, like Peter, we perceive that He is no respecter of persons, but that in every nation he that feareth Him and worketh righteousness is acceptable to Him.