In response to the proposition that "Islam does not worship the same God as do Christians and the Jews." (Letters 16/8 & 18/8)
The Koran teaches:
Unbelievers say, "God is the Messiah, son of Mary." (Koran 5:16-17; 4:171)
"The Messiah, son of Mary, was no more than an apostle." (Koran 5:75)
"Those who say God has begotten a son, preach a monstrous falsehood." (Koran 19:88)
Unbelievers are those who say, "God is one of three." (Koran 5:73)
"God is the enemy of the 'Unbelievers'."(Koran 2:98)
Christ Himself taught He was God incarnated (John 8:23,25,58; 16:28) and that God is indeed Tri-une, (John 14:9; Matthew 28:19; Genesis 1:26) so, the contradictory God of the Koran teaches Christ Himself to be both an 'Unbeliever' and "an enemy of God." They respect Christ as an apostle and prophet (Koran 2:136; 3:83-86) but condemn Him as an 'Unbeliever'. (Koran 2:98; 3:9-12) Clearly, the 'god' of Islam and the God of the Jews and the Christians is not the same God.
Islam claims for itself to be "the only true faith in God's sight." (Koran 3:19) This religious-ideology claims to have supplanted the religion which the one true God initiated through His ancient patriarch Abraham's Hebrew-Jewish people, from which people, He declared through His prophets, would eventually issue His Jewish-Christ-Messiah as the one and only Saviour of all mankind as attested to in the ancient Scriptures, "God Himself will come and save you." (Isaiah 35:4) The Saviour confirmed His Divinity and its Tri-une Nature when He said, "Who sees Me, sees the Father, and henceforth you have seen Him." (John 14:9) "Before ever Abraham was, I Am." (John 8:58; Genesis 3:14) "No one can come to the Father except by Me." (John 14:6) "Salvation is of the Jews." (John 4:22-24)
600 years after the God-Messiah had completed His mission, along comes Muhammad with his ideological claim of Islamic supremacy to challenge the Messiah's role as Saviour and deny His God-Son-Divinity and Personal role in the communal life of the Tri-une Godhead.
(Luke 1:35; Koran 19:88; 1 John 5:7)
It was the Messiah Himself Who said, "Eternal life is to know the Father and the Son Whom He has sent." (John 17:3) As the Son also prophesied, "The time will come when he who kills you will think he is doing a holy duty for God, and he will do this because he knows neither the Father nor Me. I tell you this so that when it happens, you will remember I told you." (John 16:2-4)
So, it is clear. Muslims 'know' only their 'one-god' Allah. They know not the Communal Divinity of the Father and the Son, as they know not that, "There are three who give testimony in Heaven, the Father, the Word-Christ, and the Holy Spirit. And these three are One." (1 John 5:7)
This latter is the true God of Abraham, Isaac and Jacob. This true God is the God of the Jew and of the Christian.
The true Tri-une God, the Muslim is yet to discover. (The Islamic contradictions are rooted in the 'pretending-to-be-Gabriel' angel-source of their Koran.)