Final answer:
Augustine was influenced by Platonic thought, which helped him conceptualize the idea of the City of God as distinct from the City of Man, correlating to Plato's realm of forms versus the material world. He integrated these ideas into his Christian faith, emphasizing the superiority of the spiritual and the need for divine grace.
Step-by-step explanation:
St. Augustine found Platonic thought to be influential in his intellectual development, particularly at the point in his life when he was grappling with questions of faith and the nature of reality. Although he transformed Plato's ideas to fit his Christian worldview, the Platonic understanding of the distinction between the imperfect material world and a perfect, unchangeable, spiritual realm resonated with Augustine. In his work The City of God, Augustine articulates a vision that juxtaposes the City of Man—transient, flawed, and of this world—with the City of God—eternal, perfect, and the ultimate object of human striving. The Platonic influence shows in his emphasis on the spiritual realm being superior to the material and the ultimate insignificance of earthly concerns in comparison to eternal truths. However, Augustine Christianized these Platonic ideas, integrating them within a framework that emphasized the need for divine grace and the redemptive power of faith in God, diverging from purely Platonic interpretations.