Muslims often rightly state that the word ‘Trinity’ is not mentioned in the Bible. However, to be consistent, those that do so must also acknowledge that the word ‘Tawhid’ is not mentioned in the Qur’an either. Dr. K. Mathison rightly said this: “The Doctrine of the Trinity is certainly a good and necessary consequence of what is expressly set down in Scripture.” (Mathison, 2019).
Regarding the Bible, what we can say with absolute certainty is that the concept of the Trinity is found in both the Old and New testaments. Meantime, there is much false teaching within Islam itself concerning the Christian faith. For example, in a booklet published by the Islamic Dawah Centre International in 2008, titled ‘Islam at a Glance’ and basing their claim on S.3:84, the authors begin on page one with this: “Islam is not a new religion. It is in essence the same message and guidance, which Allah revealed to all His Prophets”. This is untrue. Each prophet of the Old Testament agreed with the one who came before him. Meanwhile, more than six hundred years later, Muhammad taught the exact opposite, including the erroneous charge that Christianity promotes polytheism.
The Christian Bible expressly teaches that there is only one God, and the polytheism of the nations around Israel is strongly condemned in the Old Testament. Only Yahweh is God, and there is no other (Isa. 44:6-20). Scripture expressly teaches that the Father is God (Romans 1:7; Gal.1:1; 1 Tim.1:2) and it explicitly identifies the Son as God. For example, the Apostle John identifies the Word as God, while at the same time being distinguished from God, since He is with God. Then in verse 14 of the same chapter, Jesus is identified as the Word (John 1:1-14). Scripture also expressly teaches that the Holy Spirit is God, as in Acts chapter five where we learn that lying to the Holy Spirit is equated with lying to God.
Concerning prophecy, the Gospel of Mark begins by quoting the prophet Isaiah, thereby identifying Jesus as God (Isa. 40:3). Writing more than 600 years before the birth of the Messiah, Isaiah is comforting the people with the promise that one day the LORD will come to Israel. The word ‘LORD’ is a transliteration of God’s personal, eternal name in Hebrew – Yahweh. Jesus is the one in the gospel of Mark who fulfils this prophecy from Isaiah, written hundreds of years before Christ was born. Clearly, the Bible teaches that Jesus is God.
Throughout the New Testament Jesus is worshipped (Matt.2:2), and He accepts worship (John 20). Jesus is also identified as the Creator (John 1:3; cf. Heb.1); He sustains all created things (Col. 1:17), and He is sovereign over nature (Matt. 8:23-27). And Jesus forgives sin. For example, when Jesus healed a paralysed man, He also told him that his sins were forgiven. Jesus tells him that He has forgiven his sin simply because he had faith in who Jesus was (Matt. 9 1-8). Jesus forgave the man’s sins by His own will and power. Crucially, the Bible teaches that Jesus will be the Judge on the last day (John 5:22). Forgiving sin and judging the world are both prerogatives of God alone. And God protects His Word, so none of this would be said of Jesus if He were not God.
Finally, Scripture expressly teaches that while they are one, the Father, Son, and Holy Spirit are distinguished from each other, even though each person is God. Scripture distinguishes the Father from the Son in the following ways: The Father sent the Son (John 3:16f; Gal. 4:4); the Father and Son love each other (John 3:35; 5:20; 14:31); they speak to each other (John 11:41f); they know each other (Matt. 11:27); and the Son is our advocate with the Father (1 John 2:1). None of this makes sense unless the Father is distinguished from the Son. Scripture also distinguishes the Son from the Holy Spirit, since He descends on the Son at His baptism (Luke 3:22). And the Holy Spirit is another Comforter in John 14, whom the Son sends (15:26; cf. 16:7). Also, the Holy Spirit glorifies the Son in John 16. And Scripture distinguishes the Father from the Holy Spirit, since the Father sends the Holy Spirit in John 14 (14:15-15:26). Moreover, the Holy Spirit is said to intercede with the Father (Rom. 8:26f).
The three persons of the godhead are distinguished in numerous other passages in the Bible. Perhaps most well-known is when Jesus commissions His disciples to baptise the nations in the name of the Father, the Son, and the Holy Spirit (Matt. 28:19). This leaves us with a question: How are we to understand God so that all that is expressly taught about Him in Scripture is true? Due to early heresies, in which heretics insisted on using only biblical terms while denying biblical content, the Church was forced to think through this question. Considering everything that Scripture teaches about God, it was worked out theologically in this way: The distinguishing between the essence (Gk. ousia) of God, which refers to the being of God, to that which constitutes deity, and the persons (Gk. Hypostases) within God. This is the result of what Christians refer to as the Doctrine of the Trinity, as laid down in the Nicene Creed.
To know the truth about God and what our response ought to be, it is first necessary to understand how God has revealed Himself in His Word. Please read the article, "Has the Bible been Changed?" and check out the Bible references above. Please do also pray, asking God to reveal to you the truth about who He is. Finally, if you haven’t done so already, please watch the videos in our ‘52 Questions Series’. In particular, “What is God Like?” and “What is the Gospel?”