The term Trinity is not specifically used in scripture but is clearly implied in its teaching. From Genesis to Revelation, God is revealed as Father, Son, and Holy Spirit. 1 John 5 v 7 clearly states this revelation of God’s essence. ‘For there are three that bear record in heaven, the Father, the Word and the Holy Spirit; and these three are one’ (KJV). The biblical term for this unity of the three divine persons is Godhead, and is used in Acts 17:29; Romans 1:20; and Colossians 2:9.
The term Trinity has been used since early Church times to denote the unique nature of the Godhead. ‘Tri’ denotes the three persons of God and unity denoting God’s Oneness. So the term Trinity was derived from Tri-unity. The term Trinity is reference to God Himself. He is One; He is three; distinguishable yet inseparable; One in operation; three in manifestation. The Father is God; Jesus Christ is God; the Holy Spirit is God.
The early Church fathers faced with the heresies of Unitarianism and Tri-theism, compiled the Athanasius Creed in 356 A.D. In question 24 of this book under the heading X11. Isa – Jesus Christ and the Trinity the Athanasius Creed is stated in its full text. Please refer to it.
In the Qur’an Surah 5 Al Ma’idah ayat 72-73 it states: ‘They do blaspheme who say: ‘Allâh is Christ the son of Mary.’ But said Christ: ‘O Children of Israel! Worship Allâh, my Lord and your Lord.’ Whoever joins other gods with Allâh – Allâh forbid him The Garden (Paradise), and the Fire (Hell) will be his abode. There will for the wrongdoers be no one to help. They do blaspheme who say: Allâh is one of three in a Trinity: for there is no god except One God. If they desist not from their word of blasphemy verily a grievous penalty will befall the blasphemers among them.’
In Surah 4 Al Nisa ayah 171 there is an injunction: ‘O People of the Book! (Christians and Children of Israel). Commit no excesses in your religion: nor say of Allâh anything but the truth. Christ Jesus the son of Mary was a Messenger of Allâh, and His Word which He bestowed on Mary, and a Spirit proceeding from Him: so believe in Allâh and His Messengers. Say not ‘Trinity’: desist. It will be better for you: For Allâh is One God: Glory be to Him: (Far Exalted is He) above having a son: To Him belongs all things in the heavens and on earth. And enough is Allâh as a Disposer of affairs.’
Muhammed is known to have interacted with groups of people who claimed to be Christian, such as his first wife Khadijah and her close friend, who were both Maryamites and worshipers of Mary. In Surah 5 Al Ma’ida ayah 116, it says: ‘And behold! Allâh will say: ‘Oh Jesus the son of Mary! Didst thou say unto men, ‘Worship me and my mother as gods in derogation of Allâh?’’ Muhammed rightly rebuked the People of the Book who worshipped Mary. It becomes apparent as you read the Qur’an that Muhammed had difficulty understanding the true Christian concept of the Oneness of the Trinity and thought Christians worshipped three distinct beings, God the Father, Mary the Mother and Jesus the Son. The Athanasius’ Creed published in 356 AD a long time before Muhammed, had clarified this misunderstanding and stated that Christians do not worship three independent entities, but One God who has manifested Himself in three persons to help mankind understand His true essence.
To claim a Trinitarian view of God as Muhammed understood it is, in Muslim theology, the highest of sins, the Islâmic equivalent of blasphemy against the Holy Spirit. Jesus taught that blasphemy against the Holy Spirit was the only unforgivable sin. What Jesus meant when making this statement was that this blasphemy occurred when a person attributed the work of God to Satan or an evil spirit. In Jesus’ time on earth, some religious leaders were saying that the miracles Jesus did were the work of evil spirits. Jesus countered this argument by saying that a kingdom cannot be divided against itself and stand (Luke 11:17-23). The Qur’an endorses Isa (Jesus) as the Messiah or Anointed One. To understand how the Qur’an can make this claim we must look at the Qur’anic references to Jesus in Surah 3 Al ‘Imran ayat 42-56:
i) Jesus had a supernatural birth by proclamation of the Word in Mary’s womb, not by human intercourse or the ‘spirit of incubus (demonic simulation of intercourse)’. His conception was Holy, Pure and Divine (ayat 42-43, 47).
ii) The Names and Titles of Jesus (45,49,53). He is called Word, Christ, Jesus, Apostle, Lord, Prophet and 26 other names of honour in the Qur’an
iii) Christ’s Name must be Honoured throughout the world (45)
iv) The Righteousness of Christ (46)
v) God (Allâh) is the Father of Jesus in his incarnation on earth (47) vi) The Gospel of Christ is the Good News of Salvation (48)
vii) The Miracles of Jesus (49)
viii) Jesus was sent to confirm/fulfil the Law of Moses (50)
ix) We must obey Jesus and walk in the Way that is Straight (The Right Path) (50-51)
x) Jesus has many Disciples and they are Muslims – submitted to God’s (Allâh’s) will (52)
xi) God raised Jesus to Himself (55)
xii) Allâh would deliver Jesus from all falsehood against his name – Jesus was unjustly tried and crucified for crimes He did not commit (55)
xiii) We must follow Jesus and put our Faith in Him because rejection of these truths will result in punishment (55-56)
So, to blaspheme the name of Jesus and to deny his Anointed role as the resurrected Christ, Saviour and Lord is to blaspheme God (Allâh) and His redemptive work on earth through Jesus.