Julius Firmicus Maternus was a Roman writer educated in classical Greek traditions who lived during the reign of Emperor Constantine I and his successors. His career spanned roles as a public advocate, an astrologer, and ultimately, a Christian apologist. Manuscripts identify him by his name and status as a "vir clarissimus" and senator, sometimes noting him as "the younger" or "the Sicilian."

He is known for two significant works. The first is "Matheseos libri octo" (Eight Books of Astrology), believed to be the most extensive surviving text on Roman astrology, written around 334–337 AD. This work was dedicated to Lollianus Mavortius and represents one of the last comprehensive handbooks of "scientific" astrology in the West before the 12th century. The second major work is "De errore profanarum religionum" (On the Error of Profane Religions), composed around 346 AD. In this text, dedicated to Constantine's sons, Firmicus Maternus vehemently criticizes pagan beliefs and practices, urging the emperor to suppress them.

Firmicus Maternus authored "Matheseos libri octo" (Eight Books of Astrology), which stands as the most comprehensive surviving text on Roman astrology. Composed between 334 and 337 AD, this extensive handbook was dedicated to Lollianus Mavortius, the governor of Campania, whose knowledge and support were instrumental in its creation. The work is considered a significant contribution to the field of "scientific" astrology as it was understood in the classical world, circulating in the West for centuries. It represents a late example of such detailed astrological treatises before the influence of Arabic texts became prominent in the 12th century. The text was first printed by Aldus Manutius in 1499 and has been reprinted numerous times, indicating its enduring interest for scholars and practitioners of astrology.

Around 346 AD, Firmicus Maternus produced "De errore profanarum religionum" (On the Error of Profane Religions), a work dedicated to the sons of Emperor Constantine. In this treatise, he sharply condemned pagan religious beliefs and practices, urging the imperial authorities to eradicate them as a divine imperative. The book is divided into two parts: the first (chapters 1-17) critiques the objects of worship in Oriental cults, while the second (chapters 18-29) scrutinizes various ritualistic formulas and practices, with a particular focus on perceived homosexual activities. This section reflects a strong animosity and a desire to reject foreign influences, echoing earlier Roman sentiments against the Hellenization of their religion and culture.

The identification of Julius Firmicus Maternus as the author of both the astrological "Matheseos" and the Christian polemic "De errore profanarum religionum" was established through stylistic analysis, particularly idiosyncratic vocabulary and syntax, by scholars like Clifford Herschel Moore. Historically, the stark contrast between the two works led some 19th-century readers to believe they were written by different individuals. Dating the "Matheseos" to 336 AD, as proposed by Theodor Mommsen, places it before "De errore profanarum religionum," suggesting the astrological work predates Firmicus Maternus' conversion to Christianity. He received a pagan classical education and lived during a period of significant religious transition in the Roman Empire.