The study of documental sources from New Spain (today Mexico) provides a window into the beliefs of the Otomi people regarding what is called ‘soul’ in Western culture. To begin, I shall explain who these people were and how they interacted with their Nahua neighbors in central Mexico. Then, I analyze the words, in the Nahuatl and Otomi languages, belonging to semantic fields that relate to the Christian concept of the soul. We find many calques, or semantic loans, revealing that these two language groups shared beliefs in multiple animic essences that could survive the death of the body. Finally, I present evidence from colonial period documental sources, showing how the beliefs of the Otomi were affected by the teachings of Christian priests. In these texts, one may observe the resistance of the Otomi people as a reaction to the efforts of the missionaries to impose Catholic doctrine and ritual on the native population.