This chapter demonstrates how the missionary reports produced in colonial Brazil impacted the theological debates surrounding atheist peoples in the Americas before European contact. Some studies have investigated the relevance of sources about non-European people in the development of the concept of atheism. However, the theological and philosophical impact on this category from the sources produced on the indigenous peoples of the Americas, especially the Tupi people, seems to have been overlooked. Although some anthropological and theological studies, such as those by Pierre and Hélène Clastres and Pedro Chutégui, have examined some of these sources, no work has approached the pre-Columbian sources with the centrality they should have in European Catholic theological production on atheism. The case of the Tupi people impacted fundamental theological issues discussed in the works of Luís de Molina, such as the possibility of salvation outside the Church, invincible ignorance, and the rational cognoscibility of God.