The three monotheistic religions -- Judaism, Christianity and Islam -- all profess to share one fundamental concept: belief in Allah as the Supreme Being, the Creator and Sustainer of the Universe. Known as Tawheed (monotheism) in Islam, this concept of the Oneness of God was stressed by Moosaa (Moses), may Allah exalt his mention, in a Biblical passage known as the "Shema" or the Jewish creed of faith: "Hear, O Israel: The Lord our God is one Lord." [Deuteronomy 6:4]
It was repeated word-for-word approximately 1500 years later by ‘Eesaa (Jesus), may Allah exalt his mention, when he said: "...The first of all the commandments is, Hear, O Israel; the Lord our God is one Lord." [Mark 12:29]
Muhammad may Allah exalt his mention, came along approximately 600 years later, bringing the same message again (which means): "And your God is One God: There is no deity (worthy of worship) except Him ..." [Quran 2:163]
Christianity has deviated from the concept of the Oneness of God, however, into a vague and mysterious doctrine that was formulated during the fourth century CE. This doctrine, which continues to be a source of controversy both within and without the Christian religion, is known as the Doctrine of the Trinity. The Christian Doctrine of the Trinity simply states that God is the union of three divine persons -- the Father, the Son and the Holy Spirit -- in one divine being.
If that concept, put in basic terms, sounds confusing, the flowery language in the actual text of the doctrine lends even more mystery to the matter:
"...we worship one God in Trinity, and Trinity in Unity... for there is one Person of the Father, another of the Son, another of the Holy Ghost is all one... they are not three gods, but one God... the whole three persons are co-eternal and co-equal... he therefore that will be saved must thus think of the Trinity..." (Excerpts from the Athanasian Creed)
Let us put this together in a different form: one person, God the Father + one person, God the Son + one person, God the Holy Ghost = one person, God the What? Is this English or is this gibberish?
It is said that Athanasius, the bishop who formulated this doctrine, confessed that the more he wrote on the matter, the less capable he was of clearly expressing his thoughts regarding it.
How did such a confusing doctrine start?
Trinity in the Bible
References in the Bible to a Trinity of divine beings are vague, at best.
In Matthew 28:19, we find Jesus, may Allah exalt his mention, telling his disciples to go out and preach to all nations. While the "Great Commission" does mention the three persons who later became components of the Trinity, the phrase "...baptizing them in the name of the Father, and of the Son, and of the Holy Ghost" is quite clearly an addition to Biblical text -- that is, not the actual words of Jesus, may Allah exalt his mention -- as can be seen by two factors:
1. Baptism in the early Church, as discussed by Paul in his letters, was done only in the name of Jesus.
2. The "Great Commission" found the first gospel written by Mark, bears no mention of Father, Son and/or Holy Ghost (see Mark 16:15).
The only other reference in the Bible to a Trinity can be found in the Epistle of I John 5:7, Biblical scholars of today, however, have admitted that the phrase "...there are three that bear record in heaven, the Father, the Word, and the Holy Ghost: and these three are one” is definitely a "later addition" to Biblical text, and it is not found in any of today's versions of the Bible.
Therefore, it can be seen that the concept of Trinity of divine beings was not an idea put forth by Jesus, may Allah exalt his mention, or any other prophet of Allah. This doctrine, now subscribed to by Christians all over the world, is entirely man-made in origin.
The Doctrine Takes Shape
While Paul of Tarsus, the man who could rightfully be considered the true founder of Christianity, did formulate many of its doctrines, the Trinity was not among them. However, he did lay the groundwork for such, when he put forth the idea of Jesus, may Allah exalt his mention, being a "divine Son." After all, a Son does need a Father, and what about an intermediary for God's revelations to man? In essence, Paul named the principal players, but it was the Church that later put the matter together.
Tertullian, a lawyer and presbyter of the Church in Carthage in the third century CE, was the first to use the word "Trinity" when he put forth the theory that “the Son and the Spirit participate in the being of God, but all are of one being of substance with the Father.”
A Formal Doctrine is Drawn Up
When controversy over the matter of the Trinity blew up in 318 CE between two churchmen from Alexandria -- Arius, the deacon, and Alexander, his bishop -- Emperor Constantine stepped into the fray.
Although Christian doctrine was a complete mystery to him, he did realize that a unified church was necessary for a strong kingdom. When negotiation failed to settle the dispute, Constantine called for the first ecumenical council in Church history in order to settle the matter once and for all.
Six weeks after the 300 bishops first gathered at Nicea in 325 CE, the doctrine of the Trinity was finalized. The God of the Christians was now seen as having three essences, or natures, in the form of the Father, the Son, and the Holy Spirit.