Saint Augustine, Bishop of Hippo, (354 – 430 AD) was one of the most important and influential figures in the history of Christianity, and is often referred to as one of the "Church Fathers." Born to a pagan father and a Christian mother, he received a traditional pagan education, culminating in the study of rhetoric, and himself became a teacher of rhetoric. He was a prolific author, writing over a hundred works including Biblical commentaries, sermons, philosophical and theological essays, and letters.
The notion of a faith journey appears most clearly in his Confessions, a spiritual autobiography that recounts his gradual evolution from Christianity to Manicheanism to Platonism and eventually converting back to Christianity. In this extremely long and detailed narrative, Augustine shows faith to be not just a simple matter of belief but a constant struggle with his carnal nature, with faith always as an ultimate goal but many obstacles constantly needing to be surmounted in the journey towards a more perfect faith.
In Confessions and De Doctrina Christiana, Augustine develops the concept of Jesus as uniquely both the path and the destination of the faith journey. According to Augustine, faith in Jesus is our ultimate goal but given original sin, we would be incapable of achieving that goal with the sacrifice of Jesus on the cross that atoned for original sin, making Jesus also the path. Thus, in Augustine's terms, Jesus and only Jesus is both a thing to be used and a thing to be enjoyed, as opposed to God, who is only to be enjoyed and all other things which are only to be used for the sake of God.
Augustine in De Doctrina Christiana talks about the relationship between reason and faith, and pagan learning and Christianity, in terms of the metaphor of the gold taken from Egypt by the Jews in Exodus. Like the Egyptian gold, the tools of reason and pagan learning can be used in service of interpreting the Bible, creating sermons, defending Christianity against the arguments of the pagans, and generally furthering the cause of Christianity. He argues that the more we know about and understand the world, the better we can interpret the signs (words and images) found in the Bible.