Trinity

===Before the Council of Nicaea===
[[File:Dogmatic sarcophagus.JPG|thumb|right|Detail of the [[Early Christian art and architecture|earliest known artwork]] of the Trinity, the [[Dogmatic Sarcophagus|Dogmatic or Trinity Sarcophagus]], {{circa}} 350 ([[Vatican Museums]])

Three similar figures, representing the Trinity, are involved in the creation of [[Eve]], whose much smaller figure is cut off at lower right; to her right, [[Adam]] lies on the ground{{sfn|Milburn|1991|p=68}}]]

While the developed doctrine of the Trinity is not explicit in the books that constitute the [[New Testament]], it was first formulated as early Christians attempted to understand the relationship between Jesus and God in their scriptural documents and prior traditions.{{sfn|Hurtado|2005|pp=644–648}}

An early reference to the three "persons" of later Trinitarian doctrines appears towards the end of the first century, where [[Clement of Rome]] rhetorically asks in his [[First Epistle of Clement|epistle]] as to why corruption exists among some in the Christian community; "Do we not have one God, and one Christ, and one gracious Spirit that has been poured out upon us, and one calling in Christ?" (1 Clement 46:6).<ref>Ehrman, Bart D. ''The Apostolic Fathers''. Vol. 1. Loeb Classical Library, 2003, 119. Ehrman further notes (fn. 97) Clement is alluding to Ephesians 4:4–6. Also see 1 Clement 58:2.</ref> A similar example is found in the first century [[Didache]], which directs Christians to "baptize in the name of the Father and of the Son and of the Holy Spirit".<ref>Ehrman, Bart. ''The Apostolic Fathers'', Vol. 1. Harvard University Press, 2003, pp. 411, 429.</ref>

[[Ignatius of Antioch]] similarly refers to all three persons around AD 110, exhorting obedience to "Christ, and to the Father, and to the Spirit".<ref name="ignatius"/> Though all of these early sources do reference the three persons of the Trinity, none articulate full divinity, equal status, or shared being as elaborated by Trinitarians in later centuries.{{citation needed|date=September 2022}}

The pseudonymous [[Ascension of Isaiah]], written sometime between the end of the first century and the beginning of the third century, possesses a "proto-trinitarian" view, such as in its narrative of how the inhabitants of the sixth heaven sing praises to "the primal Father and his Beloved Christ, and the Holy Spirit".{{sfn|Hurtado|2005|pp=595–599}}

[[Justin Martyr]] (AD 100 – c. 165) also writes, "in the name of God, the Father and Lord of the universe, and of our Saviour Jesus Christ, and of the Holy Spirit".<ref name="first-apology"/> Justin Martyr is the first to use much of the terminology that would later become widespread in codified Trinitarian theology. For example, he describes that the Son and Father are the same "being" ({{lang|grc-Latn|ousia}}) and yet are also distinct faces ({{lang|grc-Latn|prosopa}}), anticipating the three persons ({{lang|grc-Latn|hypostases}}) that come with [[Tertullian]] and later authors. Justin describes how Jesus, the Son, is distinguishable from the Father but also derives from the Father, using the analogy of a fire (representing the Son) that is lit from its source, a torch (representing the Father).{{sfn|Hurtado|2005|pp=646}} At another point, Justin Martyr wrote that "we worship him [Jesus Christ] with reason, since we have learned that he is the Son of the living God himself, and believe him to be in second place and the prophetic Spirit in the third" (1 Apology 13, cf. ch. 60).

[[File:Albrecht Dürer - Adoration of the Trinity (Landauer Altar) - Google Art Project.jpg|thumb|left|The ''Adoration of the Trinity'' by [[Albrecht Dürer]] (1511)

From top to bottom: Holy Spirit (dove), God the Father and Christ on the cross]]
The first of the early Church Fathers to be recorded using the word "Trinity" was [[Theophilus of Antioch]] writing in the late 2nd century. He defines the Trinity as God, his Word ({{lang|la|Logos}}) and his Wisdom ({{lang|la|Sophia}})<ref name="theophilus2"/> in the context of a discussion of the first three days of creation, following the early Christian practice of identifying the Holy Spirit as the Wisdom of God.<ref>Theophilus, ''To Autolycus'', 1.7 Cf. Irenaeus, ''Against Heresies'', 4.20.1, pg. 3<br>''Demonstration of the Apostolic Preaching'', pg. 5</ref>

The first defense of the doctrine of the Trinity was by [[Tertullian]], who was born around 150–160 AD, explicitly "defined" the Trinity as Father, Son, and Holy Spirit and defended his theology against [[Praxeas]],<ref name="tertullian"/> although he noted that the majority of the believers in his day found issue with his doctrine.<ref name="against-praxeas1"/>

[[File:Bartolomé Esteban Murillo - The Heavenly and Earthly Trinities - 1681-82.jpg|thumb|The "Heavenly Trinity" joined to the "[[Holy Family|Earthly Trinity]]" through the [[Incarnation (Christianity)|Incarnation]] of the [[God the Son|Son]]–''[[The Heavenly and Earthly Trinities]]'' by [[Bartolomé Esteban Perez Murillo|Murillo]] (c. 1677)]]

St. Justin and Clement of Alexandria referenced all three persons of the Trinity in their [[Doxology|doxologies]] and [[Basil of Caesarea|St. Basil]] likewise, in the evening lighting of lamps.{{sfn|Mulhern|1967|p=205}}

[[Origen of Alexandria]] (AD 185 – c. 253) has often been interpreted as [[Subordinationist]] – believing in shared divinity of the three persons but not in co-equality. (Some modern researchers have argued that Origen might have actually been anti-Subordinationist and that his own Trinitarian theology inspired the Trinitarian theology of the later [[Cappadocian Fathers]].){{sfn|Ramelli|2011a}}{{sfn|Barnard|1970|pp=172–188}}

The concept of the Trinity can be seen as developing significantly during the first four centuries by the [[Church Fathers]] in reaction to theological interpretations known as [[Adoptionism]], [[Sabellianism]], and [[Arianism]]. Adoptionism was the belief that Jesus was an ordinary man, born of Joseph and Mary, who became the Christ and Son of God at his baptism. In 269, the [[Synods of Antioch]] condemned [[Paul of Samosata]] for his Adoptionist theology, and also condemned the term {{lang|grc-Latn|[[homoousios]]}} ({{lang|grc|ὁμοούσιος}}, "of the same being") in the modalist sense in which he used it.{{sfn|Chapman|1913}}

Among the [[Nontrinitarianism#Beliefs|nontrinitarian beliefs]], [[Sabellianism]] taught that the Father, the Son, and the Holy Spirit are essentially one and the same, the difference being simply verbal, describing different aspects or roles of a single being.{{sfn|Chadwick|1993|p=87}} For this view Sabellius was excommunicated for [[Heresy#Christianity|heresy]] in Rome c. 220.