The Trinitarian view of Christianity came into being many years after the disappearance of Jesus (peace be upon him). Undoubtedly, it was not professed by Jesus nor by the other prophets (peace be upon them all). As a matter of fact, the true followers of Jesus (peace be upon him) continued to affirm the Oneness of God until about 90 A.D. This belief in the Unity of God was manifested in the Shepherd of Hermas, which was written during this period and regarded as a book of revelation by the earlier Christians. Aside from its precept on the Oneness of God, this scripture also contains other related commandments on sincerity, truthfulness, purity, patience, uprightness, piety and self-control. More specifically, the first of these commandments states:" First of all, believe that God is One and that He created all things and organized them out of what did not exist made all things to be, and He contains all things but alone is Himself uncontained. Trust Him therefore and fear Him and, fearing Him be self-controlled. Keep this command and you will cast away from yourself all wickedness, Put on every virtue of uprightness, and you will live to God if you keep this commandment ".
The Apostles' Creed " I believe in God the (Father) Almighty" began to be known to the earlier Christians in 120 A.D. The word father was, in fact, added to this creed only between 180 A.D. and 210 A.D. A number of the Apostolic Church leaders condemned this innovation, for they found it abominable to inject new ideas into the original teachings of Jesus (peace be upon him) ".
One of the early leaders of the Apostolic Church was Iranaeus, who succeeded Bishop Pothinus of Lyons in 177 A.D., after the latter's brutal murder. In 190 A.D., Iranaeus wrote to Pope Victor to stop the massacre of dissenting Christians whose belief did not agree with the doctrine of the Rome-based Pauline Church. Iranaeus believed in One God and supported the doctrine of the manhood of Jesus.
Iranaeus and the rest of the early Unitarians abhored the Trinitarian dogma, being a deviation from the pristine teachings of Jesus (peace be upon him). Prior to 200 A.D. the term "Trinity" (which is now the nucleus of the Christian tenets) was not at all known to the Pauline Church. "Trinity" was derived from the Latin word Trinitas, which was first used by Tertullian in 200 A.D. to explain in Latin ecclesiastical writings the strange doctrine of the Pauline Church. Tertullian belonged to the African Church. He believed in the unity of God and identified Jesus with the Jewish Messiah. He opposed Pope Callistus for teaching that capital sin could be forgiven after doing canonical penance. Tertullian was the one who opened the way for a doctrine of salvation, at least partly by 'good works'.
Indeed, those who belonged to the Apostolic Church accepted the plain meaning of the words spoken by Jesus (peace be upon him), as embodied in the earlier scriptures. Without resorting to mysterious dogmas, they continued to uphold the article of faith "I believe in God, the Almighty" until 250 A.D.. In his attempt to refute the Trinitarian view of Christianity, Lactaneus (orthodox father) wrote in 310 A.D. that, "Christ never calls himself God." In 320 A.D., Eusebius of Nicomedia wrote, "Christ teaches us to call his father the true God and to worship Him".
These early Unitarian leaders were courageous enough to expose their views to refute the Trinitarian dogmas, in spite of the persecution campaign against them. Their real champion, however, was Arius who in 318 A.D. popularly opposed the Pauline view that Jesus was in reality the "Son of God" and "consubstantial and coeternal with the father". One of the arguments propagated by Arius was: "If Jesus was in reality the 'Son of God', then it followed that the father must have existed before him (the son). Therefore, there must have been a time when the son (Jesus) did not exist. Therefore, it followed that the son was a creature composed of an essence or being which had not always existed. Since God is in essence Eternal and Ever-existent, Jesus could not be of the same essence as God". In 321 A.D., Arius popularly confronted Bishop Alexander the forerunner of the Pauline Church. In refuting the Trinitarian belief, Arius argued that "God is absolutely One... God is alone Ingenerate, alone Eternal, alone without beginning, alone Good, alone Almighty, alone Unchangeable and Unalterable, and that His being is hidden in eternal mystery from the outward eye of every creature". Four years later (in 325 A.D.), Emperor Constantine convened the First General Council at Nicea, now called Iznik, a Turkish village in north-west Asia Minor. This Council was attended by 318 bishops from Spain to Persia. Emperor Constantine allegedly aimed at reconciling the prelates (particularly Arius and Alexander) who were involved in the Trinitarian controversy. Bishop Alexander, however, could not attend this Ecumenical Council, so he delegated Athanasius to represent him and the Pauline Church. Although the Council ratified the Trinitarian Creed, the pro-Arians continued to practice their own Unitarian views.
In 380 A.D., Emperor Theodosius of Rome made the orthodox faith (the Trinitarian-based Catholic faith) obligatory for all his subjects, hence the state religion since then. By 381, the Council of Constantinople, the Second General Council which was attended by 186 bishops, gave the finishing touch to the doctrine of three persons in one God. Emphatically, this Council asserted the godhead of the Holy Spirit. By 383 A.D., Theodosius threatened to punish all who would not believe in the doctrine of Trinity. This threat, however, did not result in the total destruction of the Arian tenets; they have survived, and are still the foundation of the belief of many Unitarian Christians.
In the 16th century, L.F.M. Sozzini challenged John Calvin (the leader of the Protestant reformation in Switzerland) on the doctrine of Trinity. Sozzini denied the deity of Jesus and repudiated the original sin and atonement dogmas.
Another outspoken critic of the Trinitarian doctrine during the 16th century was Michael Servetus, who was regarded by many as "the founder of modern Unitarianism". He lived at a time when the Roman Catholic Church was in chaos. This situation brought about the emergence of the Protestant reformists such as Martin Luther and John Calvin. Servetus, however, found the reformists' views fundamentally at variance with the teachings of Jesus (peace be upon him) - particularly that of the belief in the Unity of God. So, in 1531 A.D., he published a book entitled "The Errors of Trinity", in which he writes: "The philosophers have invented a third separate being truly and really distinct from the other two, which they call the third Person, or the Holy Spirit, three beings in one nature... Admitting therefore these three, which after their fashion they call Persons, they freely admit a plurality of beings, a plurality of entities, a plurality of essences, a plurality of substances, and taking the word God strictly, they will have a plurality of Gods". Because of his relentless belief in the Oneness of God, Servetus was thrown into prison in Geneva on a charge of heresy. Subsequently, he was put to death slowly under the torment of fire. One of his followers, Castello, expressed his feeling ostensibly in a melancholic tone: "To burn a man is not to prove a doctrine".
In the 17th century, John Biddle (the leader of Unitarianism in England) published a pamphlet entitled: 'Twelve Arguments Refuting the Deity of the Holy Spirit". In 1645 A.D., Biddle was imprisoned for his Unitarian view. Later he was summoned to appear before the Parliament, but he firmly denied the deity of the Holy Spirit. In 1648 A.D., a "severe ordinance" was passed stating that "anyone who denied the Trinity, or the divinity of Jesus, or the Holy Spirit, would suffer death without the benefit of the clergy".
In today's modern world, those who cling to the Trinitarian doctrine identify themselves as Christians largely to quench their thirst for religion. Most of them do not deny the mysterious nature of the Trinity, which is devoid of human logic and scientific explanation. This emanates from the hard fact that it was the masterpiece of Athanasius! In other words, it was a human innovation of the worst kind, which is nothing but blasphemy against God and His Unitarian attribute. Unfortunately, most of the Christians are not even aware that such a mysterious doctrine was so controversial for many centuries, particularly during the reign of Emperor Constantine. Many Christians only know Constantine as a "hero". Let it be known, however, that Constantine - largely due to political consideration - was merely one of those who played roles of various sorts on the Trinitarian controversy. As a matter of fact, other Roman emperors and key religious leaders in Christendom - particularly during the fourth century - were involved in the Trinitarian crisis in one way or another. How they got involved in this crisis is discussed in the next section.
 E. J. Goodspeed, the Apostolic Fathers, 1950; quoted by Muhammad Ata ur-Rahman, op. cit., 1984, p.46.
 Ibid., p.7.
 Ibid., pp.74-75.
 A. M. Renwick, The Story of the Church (Bristol: Inter-Varsity Press, 1977), p.41.
 Muhammad Ata ur-Rahim, op. cit., p.7.
 Muhammad Ata ur-Rahim, Jesus: Prophet of Islam, p.88.
 Ibid., p.105.
 A. M. Renwick, the Story of the Church (Bristol: Inter-Varsity Press, 1977), p.54.
 Arend Th. Van Leeuwen, Christianity in World History: The Meeting of the Faiths of East and West, trans. By H. H. Hoskins (New York: Charles Scribner's Sons, 1964) p.275-276.
 A. M. Renwick, the Story of the Church (Bristol: Inter-Varsity Press, 1977), p.55.
 Muhammad At ur-Rahim, op. cit., p.106.
 Lonsdale and Laura Ragg, ed. and trans. From the Italian MS in the Imperial Library at Vienna, The Gospel of Barnabas (Karachi: Begum Bawamy Waqf, 1986), p.xvi.
 Muhammad Ata ur-Rahim, op. cit., p.119.
 Quoted by Muhammad Ata ur-Rahim, op. cit., p.117.
 Ibid., p.116.
 Ibid., p.142.