Elsewhere @muhammad_isa said: This is factually wrong on three points: The first is that the conflict was not about the Trinity – not once in his writings does Arius mention the Trinity, nor indeed the Third Person, the Holy Spirit. Nor is he castigated for such – it's all about Christology, that if begotten, there was a time when he (the Son) was not, and that the Son is not of the same order of substance as the Father, even though Arius declares the Son is God ... The second is that the Doctrine of the Trinity was declared long before Roman state patronage of the church, and long before Nicea. Listed below is something of a doctrinal timeline. It's a matter of note that Go is Three and God is One was declared at least 125 years before Nicaea. The Third is that there was no theological construct of the Trinity declared at Nicaea (nor indeed any Council under Roman rule) IN THE APOSTOLIC ERA: A Trinitarian formula is evident in the very earliest Christian Scriptures: 57AD: "Wherefore I give you to understand, that no man, speaking by the Spirit of God (pneuma theos), saith Anathema to Jesus. And no man can say the Lord Jesus, but by the Holy Ghost (hagios pneuma)" (1 Corinthians 12:6) 58AD: The grace of our Lord Jesus Christ, and the charity of God, and the communication of the Holy Ghost be with you all" (2 Corinthians 13:13) 85AD: "Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit" (Matthew 28:19) THE PRE–NICENE ERA Theologians defend the three-fold baptismal confession and the relationship between Father, Son and Holy Spirit in such a manner as to counter accusations of tritheism. 70-97AD: "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?" (Clement of Rome, 1 Epistle to the Corinthians 46:6) 96AD: "... baptize in the name of the Father and of the Son and of the Holy Spirit." (Didache) 110AD: "Study, therefore, to be established in the doctrines of the Lord and the apostles ... in the Son, and in the Father, and in the Spirit." (Ignatius of Antioch, Epistle to the Magnesians, XIII) 100-150AD: "the primal Father and his Beloved Christ, and the Holy Spirit" (pseudonymous Ascension of Isaiah) 155AD: "I praise Thee, I bless Thee, I glorify Thee, through the eternal and heavenly High-priest, Jesus Christ, Thy beloved Son, through whom with Him and the Holy Spirit be glory both now (and ever) and for the ages to come." (Polycarp, Martyrdom of Polycarp 14:3) 155/7AD: "in the name of God, the Father and Lord of the universe, and of our Saviour Jesus Christ, and of the Holy Spirit" (Justin Martyr, First Apology, LXI) 195AD: "(baptism) ... in the name of God the Father, and in the name of Jesus Christ, the Son of God, who was incarnate and died and rose again, and in the Holy Spirit of God" (Irenaeus Demonstration of the Apostolic Teaching, iii) ... for the knowledge of the Father is the Son, and the knowledge of the Son of God is through the Holy Spirit" (ibid, vii) 180-185AD: "In like manner also the three days which were before the luminaries, are types of the Trinity, of God, and His Word (Logos), and His Wisdom (Sophia)." (Theophilius of Antioch, to Autolycus, II, 15) Note: First use of the word Trinity, in Greek. Its use suggests it is not a novel term, but one known to his audience) 200AD: "and praising thank the Alone Father and Son, Son and Father, the Son, Instructor and Teacher, with the Holy Spirit, all in One" (Clement of Alexandria, Pedagogy, III, 12.) 205AD: "God the Father Almighty, and Christ Jesus the Son of God, who, being God, became man ... and the Holy Spirit; and that these, therefore, are three. But if he desires to learn how it is shown still that there is one God, let him know that His power is one" (Hippolytus of Rome Against Noetus, VIII) For the Father indeed is One, but there are two Persons, because there is also the Son; and then there is the third, the Holy Spirit... The economy of harmony is led back to one God; for God is One. It is the Father who commands, and the Son who obeys, and the Holy Spirit who gives understanding: the Father who is above all, and the Son who is through all, and the Holy Spirit who is in all. And we cannot otherwise think of one God, but by believing in truth in Father and Son and Holy Spirit... And by this He showed (the Great Commission, Matthew 28:19), that whosoever omitted any one of these, failed in glorifying God perfectly. For it is through this Trinity that the Father is glorified. For the Father willed, the Son did, the Spirit manifested. The whole Scriptures, then, proclaim this truth." (Hippolytus of Rome Against Noetus, XIV) 205-215AD Tertullian Against Praxeas The first use of the term 'Trinity' in Latin. The whole document is a defence of the Doctrine of the Trinity in 31 chapters against the Monarchianism of Praxeas. Chapter 2. The Catholic Doctrine of the Trinity and Unity ... the Personal Relations of the Godhead Chapter 3. The Doctrine of the Trinity in Unity Rescued from These Misapprehensions and so on... Chapter 8. Though the Son or Word of God Emanates from the Father, He is Not, Like the Emanations of Valentinus, Separable from the Father. Nor is the Holy Ghost Separable from Either. Chapter 9. The ... Unconfused Distinction of the Several Persons of the Blessed Trinity Chapter 25. The Paraclete, or Holy Ghost. He is Distinct from the Father and the Son as to Their Personal Existence. One and Inseparable from Them as to Their Divine Nature. 225AD: "This is most clearly pointed out by the Apostle Paul, when demonstrating that the power of the Trinity is one and the same ... From which it most clearly follows that there is no difference in the Trinity, but that which is called the gift of the Spirit is made known through the Son, and operated by God the Father." (Origen, De Principiis, I, 7) "For it is the Trinity alone which exceeds every sense in which not only temporal but even eternal may be understood. It is all other things, indeed, which are outside the Trinity, which are to be measured by time and ages... (salvation) has need of both Father and Son and Holy Spirit and (he) will not obtain salvation apart from the entire Trinity, and why it is impossible to become partaker of the Father or the Son without the Holy Spirit. In discussing these points it will undoubtedly be necessary to describe the activity which is peculiar to the Holy Spirit and that which is peculiar to the Father and Son." (ibid, IV, 28) 262AD: "But some treat the Holy Trinity in an awful manner, when they confidently assert that there are not three persons ... we clear ourselves of Sabellius, who says that the Father and the Son are the same (person) ... we believe that three persons – namely, Father, Son, and Holy Spirit – are declared to possess the one Godhead: for the one divinity showing itself forth according to nature in the Trinity establishes the oneness of the nature” (Gregory the Wonderworker, A Sectional Confession of Faith 8). “But if they say, ‘How can there be three persons, and how but one divinity?’ we shall make this reply: That there are indeed three persons, inasmuch as there is one person of God the Father, and one of the Lord the Son, and one of the Holy Spirit; and yet that there is but one divinity, inasmuch as . . . there is one substance in the Trinity” (ibid., 14). 305AD: "For the kingdom of the Father, of the Son, and of the Holy Ghost, is one, even as their substance is one and their dominion one ... we worship the one deity in three persons." (Methodius, Oration on the Psalms 5). 313AD: The Edict of Milan grants Christianity — as well as most other religions — legal status. It does not constitute a replacement of traditional Roman beliefs. 325AD: Nicea affirms Father and Son are of the same substance. Nothing is said regarding the person or substance of the Holy Spirit, Arianism being purely Christological, nor is the word 'Trinity' declared or defined. 380AD: The Edict of Thessalonica makes (Nicene) Christianity the official religion of the Roman Empire. Only now can one talk of 'The Roman Church', and the above demonstrates the Doctrine of the Trinity had been established long before ... 381AD: The Council of Constantinople confirms the Creed of Nicaea and adds, regarding the Holy Spirit: "the Lord, the Giver of Life, who proceeds from the Father, who with the Father and the Son is worshipped and glorified, and who spoke through the prophets". Again, Nothing is said regarding the person or substance of the Holy Spirit, nor is the word 'Trinity' declared or defined. A Doctrine of the Holy Trinity was never dogmatically defined at Nicaea (325), Constantinople (381) nor Chalcedon (451).