St. Augustine wrote his Enchiridion in response to a request by a friend of his. This friend, Lawrence, requested that the Bishop would write a handbook on Christianity. He therefore set out to write on the three Christian cardinal virtues of faith, hope and love. One would note, however, that the majority of the work deals with faith, whereas hope and love are given a few pages at best. The saint goes through what he believes to be the major Christian doctrines and teachings, and deals with subjects such as baptism (including touching upon infant baptism), the role of angels in their interaction with mankind, the salvific nature of Christ's act, the nature of original sin and a variety of other important teachings. Naturally, then, the question would arise of what sort of theology he is trying to advance in this little Christian handbook, and just how convincing his theological vision may be.
Prior to a further exploration into these things, it is pertinent to develop a Biblical approach to the three cardinal virtues of faith, hope and love. The first epistle to the Thessalonians helps greatly in this investigation. 1st Thessalonians 1:3 and 5:8 has the triadic Pauline formula, "faith, love and hope." This formulation is used in other Pauline texts (1st Corinthians 13:13; cf. Colossians 1:4-5; 2nd Timothy 2:22), and is a clear focus in the New Testament canon. According to 1st Thessalonians, when Timothy reports back to St. Paul about the church, he speaks of their "faith and love" (3:6), implying that hope is lacking. Paul seeks to "supply what is lacking" (3:10) and restore and provide hope in the Thessalonian community, so 1st Thessalonians was written in order to console the brothers and sisters in that community and provide them with hope. With this hope, they are urged to bear in mind that they are different than the pagans and so too ought to act different – all the while expecting the sudden and imminent "day of the Lord" to come "like a thief in the night." This is important because the Christian theological vision deals with a number of different factors in light of faith, hope and love.
Indeed, in hope we are to await the parousia of our Lord. In love, we are to care for other human beings and for the world around us. In faith, we are to trust in God and believe. What St. Augustine does in this handbook is expand on these themes. He starts off seeing evil as a perversion of good, which therefore informs the remainder of this work. If evil is a perversion of good, this means that even those things which are evil also have good in them. This logically flows into discussion of angelic nature, as Lucifer began his existence as a very good angel yet in his pride, ended up perverting what was good in him and became what was evil. This in turn led to his possession of (or disguise of) a serpent in Eden (Satan is identified as the serpent in Revelation 12:9, 21:2). As he had been the guardian of Eden (interpretation of Ezekiel 28:12-17), he knew the garden well. He used this to tempt Adam and Eve to fall to sin, thereby corrupting all of the Creator's perfect creation. This, Augustine argues, is the beginning of original sin. When Cain and Abel were born, they already had original sin.
The reasoning behind original sin – in the mind of St. Augustine – is that each of us were in the body of Adam when he committed this first sin, and therefore were fallen with him (a similar line of thinking is seen in Hebrews 7:9-10 in regard to Levi being in the body of his ancestor Abraham). As we are born with this original sin, according to the saint, this is also why we have infant baptism. If baptism is intended to cleanse us of sin (in this case, original sin), he believed this was good enough justification for such an act. He also mentions the soul of a person existing even as a fetus, thus seemingly declaring that even an unborn fetus has original sin (the value of an unborn child is also seen in other early Christian writings, such as the Didache, the Epistle of Barnabas, the Didascalia and others). The baptism of infants, however, continues to be a theological controversy today. As such, we may then ask how convincing his theological vision is through the example of his support of infant baptism. There are a number of Biblical and historical considerations on this controversy.
For example, in ancient Israel, infants were initiated into the covenant through circumcision – in his letter to the Colossians, St. Paul compares this to baptism. St. Augustine's concept of original sin along with the infant mortality rate led to individuals in the Western church desiring to have their newborns baptized immediately – which is a practice that has been carried down to the present day. The practice of infant baptism is also mentioned by Hippolytus in the early 200s, so it was a practice of the church at least by that point. The major point that is often made by supporters of infant baptism is conveyed by quoting Mark 10:15, which declares that one must receive the Kingdom of God "as a little child" (or "like a little child," the rendering of which is not as strong as "as" for the argument). Some also point out that in the Acts of the Apostles, we read about entire households being baptized. Logically, we ask – would this not include infants? We may wonder, however, if these households had infants at the time, so this is mainly speculation. There are also a number of other considerations, and also arguments against infant baptism, but the approach taken by St. Augustine can be said in some ways to be rooted in Scripture and tradition, and in that sense is therefore not based solely on opinion.
One may consider Augustine's theological vision to be entirely convincing as a Christian handbook, given not only his argumentation but also his sources. He uses the Lord's Prayer and early creeds to back up his Christian theological thinking. He also goes through Christology point by point, arguing for both the humanity and the deity of Christ, the parenthood of Jesus – from Mary through the Holy Spirit, noting that the Holy Spirit is not the Father, discussion the virgin birth and other key points. In this short handbook of sorts, St. Augustine also deals with the future judgment of souls, the resurrection, the forgiveness of sins, the role of the Holy Spirit in the Church, and a variety of other key concepts. As such, he therefore covers a wide range of Christian theological teachings, and by including creeds and the commonly used Lord's Prayer, he engages in the established Christian viewpoint. One would find his theological vision convincing.
One point of contention – or complaint, rather – is the lack of time devoted to love. In chapter thirteen of 1st Corinthians, St. Paul writes that "now these three remain: faith, hope and love. But the greatest of these is love" (verse 13). If the greatest of these is love, why is most of the time devoted to faith? We do not find a statement in the canonical New Testament declaring that "God is faith" or "God is hope," but we do read in1st John 1:8 that "...God is love." God can and does provide hope and can facilitate faith, but God is love. Throughout Scripture and tradition, we are commanded to love other human beings. If God took on flesh, this suggests a relatability and commonality shared between us and God. If God exists as a Trinity, He exists in community. As humans we are created to be social beings, so that we too are encouraged to exist in community. To truly engage in and participate in this community, we must do so through love and charity. Now, St. Augustine is not lax to point these things out, but one would note that he spends less time on love and more time on faith. Perhaps, though, the main reason for this is that we need to have a clear understanding of faith, who we have faith in, why we have and need faith, how faith works, how this faith provides us with hope, and then how we can use this faith to give and receive true love between ourselves and others, ending with charity toward the human person.
Overall, St. Augustine's theological vision can be considered convincing as it not only reflected the traditional and established Christian understanding of the time, but is also primarily the Christian theological views that are still in place today. We may have a different shift and a different focus in Christianity today in a post-Vatican II world, particularly when it comes to matters of liberation theology, global and local (or contextual) theology, the preferential option for the poor and a variety of other considerations, but when it concerns Occidental Christian thinking, St. Augustine is spot on. He therefore portrays a Western Christian point of view and relates his doctrine of salvation, grace, the role of the Trinity, the nature of good and evil, his view of baptism and his doctrine of original sin through this lens. Writing toward the end of his life, this is a nice summary of what the saint has not only been searching for throughout his life, but also shows how far he has come. This short handbook may not necessarily be the definitive handbook on Western Christian theology, but it is certainly one of the classics of Christian writing.