Key Points:

• Paul’s missionary journeys and his letters (justification by faith, grace vs. law).

• Early Church Councils (Nicaea 325 AD, Chalcedon 451 AD): Defining Christ’s divinity and the Trinity.

• Augustine’s Confessions and City of God: Original sin, predestination, and church authority.

• Controversy: How Greek philosophy (Plato, Aristotle) shaped Christian doctrine.