Islam teaches absolute, uncompromising monotheism (tawḥīd). God (Allah) is one — indivisible, without partners, without equals, without offspring. The concept of God as "three" is rejected as shirk (associating partners with Allah), which the Quran calls the one unforgivable sin if one dies in that state.
"O People of the Scripture, do not commit excess in your religion or say about Allah except the truth. The Messiah, Jesus, the son of Mary, was but a messenger of Allah and His word which He directed to Mary and a soul [created at a command] from Him. So believe in Allah and His messengers. And do not say, 'Three'; desist — it is better for you."
— Quran 4:171 (Sūrat al-Nisāʾ, The Women)
"They have certainly disbelieved who say, 'Allah is the third of three.' And there is no god except one God. And if they do not desist from what they say, there will surely afflict those who disbelieve among them a painful punishment."
— Quran 5:73 (Sūrat al-Māʾidah, The Table Spread)
"Say: He is Allah, [who is] One, Allah, the Eternal Refuge. He neither begets nor is born, nor is there to Him any equivalent."
— Quran 112:1–4 (Sūrat al-Ikhlāṣ, The Sincerity)
The Quran explicitly denies that God has a son or partners. Surah 112 (al-Ikhlāṣ) is considered by classical scholars to be equivalent to one-third of the Quran in weight because it encapsulates the core Islamic creed: God is absolutely one.
The Quran calls Jesus Kalimatullah (كلمة الله — "Word of God") and Rūḥun minhu (روحٌ منه — "a spirit from Him"). But the Arabic text itself defines what these terms mean — no further interpretation needed:
"The Messiah, Jesus, the son of Mary, was only (innamā) a messenger of Allah and His Word which He directed to Mary and a spirit from Him. And do not say, 'Three'; desist — it is better for you."
— Quran 4:171 (Sūrat al-Nisāʾ) — The restrictive particle innamā ("only") limits Jesus to exactly these three titles: messenger, Word, spirit
The Arabic is explicit about what "Word" and "spirit" mean here:
"Allah gives you glad tidings of a word from Him (bi-kalimatin minhu), whose name is the Messiah, Jesus, son of Mary."
— Quran 3:45 (Sūrat Āl ʿImrān) — "A word" (kalimatin, indefinite) — a created act, not THE Word
"We blew into her (Mary) from Our Spirit (min rūḥinā)." — The same verb (nafakhna) used for Allah breathing life into Adam.
— Quran 66:12 (Sūrat aṭ-Taḥrīm) — "Blowing into" from "Our Spirit" — an act of creation, not incarnation
The Arabic grammar is unambiguous:
• Innamā (إِنَّمَا) — a restrictive particle meaning "only / nothing but." Jesus is limited to exactly what follows: messenger, Word, spirit. Everything else is excluded.
• Wa-kalimatuhu (وَكَلِمَتُهُ) — "His Word." The possessive "his" (hu) refers to Allah. This is Allah's creative command ("Kun" — "Be") directed to Mary. It is an act of God, not a person of God.
• Rūḥun minhu (رُوحٌ مِّنْهُ) — "a spirit from Him." The preposition min indicates origin/source, not shared essence. Jesus is a created being who receives spirit from Allah, not a co-eternal person.
• Bi-kalimatin minhu (بِكَلِمَةٍ مِّنْهُ) in 3:45 — "a word" (indefinite, not "the Word") from Him. The indefinite article (nun at the end of kalimatin) marks it as one instance among many — Allah's creative command, not a divine person.
Christianity teaches that God is one Being in three co-equal, co-eternal persons: Father, Son, and Holy Spirit. This is not three gods, but one God in three persons — a mystery that Orthodox, Catholic, and Protestant traditions all affirm.
"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 (ESV) — Gospel of Matthew (c. 70–90 CE)
"The grace of the Lord Jesus Christ and the love of God and the fellowship of the Holy Spirit be with you all."
— 2 Corinthians 13:14 (ESV) — Letter of Paul to the Corinthians
"But the Helper, the Holy Spirit, whom the Father will send in my name, he will teach you all things and bring to your remembrance all that I have said to you."
— John 14:26 (ESV) — Gospel of John (c. 90–120 CE)
"When the Helper comes, whom I will send to you from the Father, the Spirit of truth, who proceeds from the Father, he will bear witness about me."
— John 15:26 (ESV)
"When the Spirit of truth comes, he will guide you into all the truth, for he will not speak on his own authority, but whatever he hears he will speak, and he will declare to you the things that are to come. He will glorify me, for he will take what is mine and declare it to you."
— John 16:13–15 (ESV)
The Council of Nicaea (325 CE) formalized the doctrine against Arianism (which denied Christ's full divinity), declaring the Son "of one substance (homoousios) with the Father." The Council of Chalcedon (451 CE) further clarified Christ's two natures within the Trinitarian framework.