Throughout the text of Through Gates of Splendor, the word “Auca” relates to the Huaorani people and their language (sometimes also rendered as Waorani). The term comes from the language of a neighboring people group, the Quichua, and loosely translates as something like “savage.” Since the Huaorani’s own name for themselves was not known prior to the establishment of contacts, it was customary throughout the mid-20th century to refer to them by the name “Auca.” Now, however, most sources prefer to use the term Huaorani, especially since “Auca” is both an exonym and carries a pejorative meaning.

As a work stemming from the evangelical Christian movement, Through Gates of Splendor makes regular reference to the idea of the gospel. While the term can be used to refer to specific books of the Bible (the Gospels of Matthew, Mark, Luke, and John), its dominant use in the context of Through Gates of Splendor is as a reference to the overall message of Christianity. “Gospel” is a translation of the biblical term evangelion, meaning “good news.” The gospel message is the proclamation that Jesus Christ, the Son of God, has come into the world, died for the sins of humanity, rose to life again, and offers salvation through faith, leading to eternal life.