Unlike other commentaries that focus on debating if the gift of speaking in tongues exists or does not exist to the present day, Pentecostal Languages researches the history of tongues within Scripture. This work examines the origin of this phenomenal gift and its usage by prophets, kings, priests, angelic beings, songwriters, Jehovah, Jesus, and the Holy Spirit Himself.

Since the Apostles and others made reference to the Septuagint (the first translation of the Hebrew Bible) in their quotations to establish the authority of Scripture, so also does author D. E. Didymus canvass this ancient work by comparing the Greek texts of the Septuagint and the New Testament. The Septuagint is translated from the most ancient and surviving Hebrew scrolls of the Torah.