History of Christian theology

The doctrine of the Trinity, considered the core of Christian theology by ''Trinitarians'', is the result of continuous exploration by the church of the biblical data, thrashed out in debate and treatises, eventually formulated at the First Council of Nicaea in AD 325 in a way they believe is consistent with the biblical witness, and further refined in later councils and writings.Oxford Dictionary of the Bible, Trinity Article The most widely recognized Biblical foundations for the doctrine's formulation are in the Gospel of John, which possess ideas that originate in Platonism and Greek philosophy.

Nontrinitarianism is any of several Christian beliefs that reject the Trinitarian doctrine that God is three distinct persons in one being. Modern nontrinitarian groups views differ widely on the nature of God, Jesus, and the Holy Spirit.

Biblical canon

The Biblical canon is the set of books Christians regard as divinely inspired and thus constituting the Christian Bible. Though the early church used the Old Testament according to the canon of the Septuagint (LXX), the apostles did not otherwise leave a defined set of new scriptures; instead the New Testament developed over time.

The writings attributed to the apostles circulated amongst the earliest Christian communities. The Pauline epistles were circulating in collected form by the end of the 1st century AD. Justin Martyr, in the early 2nd century, mentions the "memoirs of the apostles", but his references are not detailed. Around 160 Irenaeus of Lyons argued for only four Gospels (the ''Tetramorph''), and argued that it would be illogical to reject ''Acts of the Apostles'' but accept the ''Gospel of Luke'', as both were from the same author. By the early 200's, Origen may have been using the same 27 books as in the modern New Testament, though there were still disputes over the canonicity of Hebrews, James, II Peter, II and III John, and Revelation, see Antilegomena. Likewise by 200 the Muratorian fragment shows that there existed a set of Christian writings somewhat similar to what is now the 27-book New Testament.

In his Easter letter of 367, Athanasius, Bishop of Alexandria, gave a list exactly the same in number and order with what would become the New Testament canon and be accepted by the Greek church. The African Synod of Hippo, in 393, approved the New Testament, as it stands today, together with the Septuagint books, a decision that was repeated by the Council of Carthage (397) and the Council of Carthage (419). Pope Damasus I's Council of Rome in 382, only if the '' Decretum Gelasianum'' is correctly associated with it, issued a biblical canon identical to that mentioned above. In 405, Pope Innocent I sent a list of the sacred books to a Gallic bishop, Exsuperius of Toulouse. Nonetheless, a full dogmatic articulation of the canon was not made until the Council of Trent in the 16th century.

Emergence of Christian theology

The emergence of Christian theology has sometimes been presented as the triumph of Hellenistic rationality over the Hebraic faith of Jesus and the early disciples. The early African theologian Tertullian, for instance, complained that the 'Athens' of philosophy was corrupting the 'Jerusalem' of faith. More recent discussions have qualified and nuanced this picture.

* From the very beginning of the Christian movement, followers of Jesus tried to make sense of the impact of Jesus of Nazareth, and began arguing about differing ways of making sense. There has never been an uncontested, unrationalized Christian faith.
* These processes of making sense initially drew upon the ideas and narratives of contemporary Judaism, which was already Hellenized in various degrees. As time went by, ideas and narratives from other Hellenistic context were drawn on, but the Jewish scriptures remained a key driver of theological development, and too sharp a distinction between Hebraic and Hellenistic is unsustainable. Some elements of early Christian theologizing previously thought to be thoroughly 'Hellenistic' (e.g., the Prologue of John's Gospel) are now regularly argued to be thoroughly Jewish.
* The ideas and narratives drawn on in this process were transformed as they were given a new context in Christian practices of devotion, community—formation and evangelism—and the extent to which borrowings from Hellenistic culture (for instance) were given new meanings in this process should not be underestimated.
* One of the characteristics of those strands of early Christianity (in the 2nd and 3rd centuries) sometimes called ' proto-orthodox' (because they are the most direct ancestors of the forms of Christianity that in the 4th century were defined as Orthodox), invested a great deal of time and energy in communication between widely spread conversations, and in pursuing a deep interest in each other's beliefs and practices. This concern and communication seems to have been as much a driver of the development of theological activity as the desire to communicate Christianity to, or make it acceptable in, a Hellenistic culture.

Patristic theology

As Christianity spread, it acquired certain members from well-educated circles of the Hellenistic world; they sometimes became bishops but not always. They produced two sorts of works: theological and "apologetic", the latter being works aimed at defending the faith by using reason to refute arguments against the veracity of Christianity. These authors are known as the church fathers, and study of them is called Patristics. Notable early Fathers include Justin Martyr, Irenaeus, Tertullian, Clement of Alexandria, Origen, etc.

A large quantity of theological reflection emerged in the early centuries of the Christian church—in a wide variety of genres, in a variety of contexts, and in several languages—much of it the product of attempts to discuss how Christian faith should be lived in cultures very different from the one in which it was born. So, for instance, a good deal of the Greek language literature can be read as an attempt to come to terms with Hellenistic culture. The period sees the slow emergence of orthodoxy (the idea of which seems to emerge from the conflicts between Catholic Christianity and Gnostic Christianity), the establishment of a Biblical canon, debates about the doctrine of the Trinity (most notably between the councils of Nicaea in 325 and Constantinople in 381), about Christology (most notably between the councils of Constantinople in 381 and Chalcedon in 451), about the purity of the Church (for instance in the debates surrounding the Donatists), and about grace, free will and predestination (for instance in the debate between Augustine of Hippo and Pelagius).

Ante-Nicene Fathers

Influential texts and writers in the 2nd century include:
* The collection known as the Apostolic Fathers (mostly 2nd century)
* Justin Martyr (c. 100/114–c. 162/168)
* Clement of Alexandria (died c. 215)
* Irenaeus of Lyons (c. 130–202)
* Various 'Gnostic' authors, such as Marcion (c. 85-c. 160), Valentinius (c. 100–c. 153) and Basilides (c. 117–138)
* Some of the texts commonly referred to as the New Testament apocrypha.

Influential texts and writers between c. 200 and 325 (the First Council of Nicaea) include:
* Tertullian (c. 155–230)
* Hippolytus (died 235)
* Origen (c. 182–c. 251)
* Cyprian (died c. 258)
* Arius (256–336)
* Other Gnostic texts and texts from the New Testament apocrypha.

First Council of Nicaea

Nicene Creed

Each phrase in the Nicene Creed, which was hammered out at the Council of Nicaea, addresses some aspect that had been under passionate discussion and closes the books on the argument, with the weight of the agreement of the over 300 bishops in attendance. [Constantine had invited all 1800 bishops of the Christian church (about 1000 in the east and 800 in the west). The number of participating bishops cannot be accurately stated; Socrates Scholasticus and Epiphanius of Salamis counted 318; Eusebius of Caesarea, only 250.] In spite of the agreement reached at the council of 325 the Arians who had been defeated dominated most of the church for the greater part of the 4th century, often with the aid of Roman emperors who favored them.

Nicene and Post-Nicene Fathers

Late antique Christianity produced a great many renowned church fathers who wrote volumes of theological texts, including SS. Augustine, Gregory Nazianzus, Cyril of Jerusalem, Ambrose of Milan, Jerome, and others. What resulted was a golden age of literary and scholarly activity unmatched since the days of Virgil and Horace. Some of these fathers, such as John Chrysostom and Athanasius, suffered exile, persecution, or martyrdom from heretical Byzantine Emperors. Many of their writings are translated into English in the compilations of Nicene and Post-Nicene Fathers.

Influential texts and writers between AD 325 and c. 500 include:
* Athanasius (298–373)
* The Cappadocian Fathers (late 4th century)
* Ambrose (c. 340–397)
* Jerome (c. 347–420)
* Chrysostom (347–407)
* Augustine of Hippo (354–430)
* Cyril of Alexandria (376–444)

Texts from patristic authors after AD 325 are collected in the Nicene and Post-Nicene Fathers. Important theological debates also surrounded the various Ecumenical Councils—Nicaea in 325, Constantinople in 381, Ephesus in 431 and Chalcedon in 451.

Papacy and primacy

The theology of the Bishop of Rome having a monarchal papacy developed over time. As a bishopric, its origin is consistent with the development of an episcopal structure in the 1st century. The origins of papal primacy concept are historically obscure; theologically, it is based on three ancient Christian traditions: (1) that the apostle Peter was preeminent among the apostles, (2) that Peter ordained his successors as Bishop of Rome, and (3) that the bishops are the successors of the apostles. As long as the Papal See also happened to be the capital of the Western Empire, prestige of the Bishop of Rome could be taken for granted without the need of sophisticated theological argumentation beyond these points; after its shift to Milan and then Ravenna, however, more detailed arguments were developed based on etc. Nonetheless, in antiquity the Petrine and Apostolic quality, as well as a "primacy of respect", concerning the Roman See went unchallenged by emperors, eastern patriarchs, and the Eastern Church alike. The Ecumenical Council of Constantinople in 381 affirmed Rome as "first among equals". By the close of antiquity, the doctrinal clarification and theological arguments on the primacy of Rome were developed. Just what exactly was entailed in this primacy, and its being exercised, would become a matter of controversy at certain later times.

Early heresies

Urgent concerns with the uniformity of belief and practice have characterized Christianity from the outset. The New Testament itself speaks of the importance of maintaining orthodox doctrine and refuting heresies, showing the antiquity of the concern. The development of doctrine, the position of orthodoxy, and the relationship between the early Church and early heretical groups is a matter of academic debate. Some scholars, drawing upon distinctions between Jewish Christians, Gentile Christians, and other groups such as Gnostics, see Early Christianity as fragmented and with contemporaneous competing orthodoxies.

The process of establishing orthodox Christianity was set in motion by a succession of different interpretations of the teachings of Christ being taught after the crucifixion. Though Christ himself is noted to have spoken out against false prophets and false christs within the gospels themselves Mark 13:22 (some will arise and distort the truth in order to draw away disciples), Matthew 7:5-20, Matthew 24:4, Matthew 24:11 Matthew 24:24 (For false christs and false prophets will arise). On many occasions in Paul's epistles, he defends his own apostleship, and urges Christians in various places to beware of false teachers, or of anything contrary to what was handed to them by him. The epistles of John and Jude also warn of false teachers and prophets, as does the writer of the ''Book of Revelation'' and 1 Jn. 4:1, as did the Apostle Peter warn in 2 Pt. 2:1-3:.

One of the roles of bishops, and the purpose of many Christian writings, was to refute heresies. The earliest of these were generally Christological in nature, that is, they denied either Christ's (eternal) divinity or humanity. For example, Docetism held that Jesus' humanity was merely an illusion, thus denying the incarnation; whereas Arianism held that Jesus was not eternally divine. Many groups were dualistic, maintaining that reality was composed into two radically opposing parts: matter, usually seen as evil, and spirit, seen as good. Orthodox Christianity, on the other hand, held that both the material and spiritual worlds were created by God and were therefore both good, and that this was represented in the unified divine and human natures of Christ.

Irenaeus (c. 130–202) was the first to argue that his "proto-orthodox" position was the same faith that Jesus gave to the apostles, and that the identity of the apostles, their successors, and the teachings of the same were all well-known public knowledge. This was therefore an early argument supported by apostolic succession. Irenaeus first established the doctrine of four gospels and no more, with the synoptic gospels interpreted in the light of '' John''. Irenaeus' opponents, however, claimed to have received secret teachings from Jesus via other apostles which were not publicly known. Gnosticism is predicated on the existence of such hidden knowledge, but brief references to private teachings of Jesus have also survived in the canonic Scripture as did warning by the Christ that there would be false prophets or false teachers. Irenaeus' opponents also claimed that the wellsprings of divine inspiration were not dried up, which is the doctrine of continuing revelation.

In the middle of the 2nd century, three groups of Christians adhered to a range of doctrines that divided the Christian communities of Rome: the teacher Marcion, the pentecostal