We (the Muslims) were holding discussions with Christians on an Islamic Discussion forum. While debating with the Christians, they made the following comments, which I'd appreciate greatly, if you responded to their comments. I shall quote them verbatim: "Finally, your quote of 4.171 (Surah 4, Ayah: 171) often misleads people and I hope you'll stop using it. First, by using the word "Trinity" Yusuf Ali implies that the Qur'an disagrees with the Christian idea of the trinity while no place in the Qur'an does it do this. Rather it speaks about the heretical position of 3 gods in one. Second, it Says Allah did not have a son. The Qur'an refers to a physical son. The Bible doesn't support this at all, it supports 'Isa as a spiritual son. Quoting 2:79 (Surah 2, Ayah 79) is also misleading because it implies the misconception that the Qur'an supports the idea that Jews and Christians changed their Books. In fact, the Qur'an does not support this but implies conclusively that this did not happen". Please, refute the claims of the Christians, in a detailed manner.

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad, sallallaahu 'alayhi wa sallam, is His slave and Messenger.

1) The Holy Qur'an states clearly and precisely the invalidity and voidness of the doctrine of trinity.

Allah Says (interpretation of meaning): {O people of the Scripture (Christians)! Do not exceed the limits in your religion, nor say of Allah aught but the truth. The Messiah 'Isa (Jesus), son of Maryam (Mary), was (no more than) a Messenger of Allah and His Word, ("Be!" - and he was) which He bestowed on Maryam (Mary) and a spirit (Ruh) created by Him; so believe in Allah and His Messengers. Say not: "Three (trinity)!" ….} [Quran 4:171].

The above Qur'anic passage addresses Christians both in the era of the Prophet, sallallaahu alaihi wa sallam, and those of this time, since all of them believe in trinity, as it is clearly stated in the book of “Sausana of Sulaiman” by Naufal Ibn Ni'matullah : 'There is no difference among Churches concerning the doctrine of Christians, that which constitutes the basis of constitution as defined by the Assembly of Niqia, is as follows: 'To believe in one god, one father who controls every creature, creator of heavens and earth, with one god (Jesus) the only son, begotten from the father in the very past times, from the light of Allah; true god from True God, begotten not created; equal and similar to father in essence and for us (humans) he came down from heaven, an embodiment of the Holy Spirit and Mary the virgin; crucified tortured, put in grave and rise again from the dead in the third day. Then, he ascended to the heaven and sat on the right of the Lord. He ………

His Kingdom will not be destroyed. Belief in the Holy Spirit, the Lord who raises from the dead, emerging from the father; he is the only son who deserves adoration and prostration; the speaker among the Prophets'. Such is the creed of the Christians.

2) The Holy Qur'an strongly denies that Allah "has a son", be Jesus or somebody else.

Allah Says (interpretation of meaning): {And they (Jews, Christians and pagans) say: Allah has begotten a son (children or offspring). Glory be to Him (Exalted be He above all that they associate with Him). …} [Quran 2:116]. He also Says: {Verily, it is of their falsehood that they (Quraish pagans) say: "Allah has begotten [offspring-the angels being the daughters of Allah]?" And, verily, they are liars!} [Quran 37:151-152]. And He Says: {…, and the Christians say: Messiah is the son of Allah. That is their saying with their mouths, resembling the saying of those who disbelieved aforetime. Allah's Curse be on them, how they are deluded away from the truth!} [Quran 9:30]. {Such is 'Isa (Jesus), son of Maryam (Mary). (It is) a statement of truth, about which they doubt (or dispute). It befits not (the Majesty of) Allah that He should beget a son [this refers to the slander of Christians against Allah, by saying that 'Isa (Jesus) is the son of Allah]. Glorified (and Exalted) be He (above all that they associate with Him). …} [Qruan 19:34-35]. {The Messiah ['Isa (Jesus)], son of Maryam (Mary), was no more than a Messenger; …} [Quran 5:75].

Then, how to claim that the Qur'an refers to "physical son" to Allah?! Far is He above having what they ascribe to Him!!!

Maybe the Christians misunderstood Allah's statement {…, and a spirit (Ruh) created by Him;} as Jesus is His son. Such an understanding is completely wrong since attributing the word Spirit is a form of honoring such a good creature. Just as it is the case in His statement {…That is the she-camel of Allah! (Do not harm it) and bar it not from having its drink!} . He Says: {A spring wherefrom the slaves of Allah will drink, …} [Quran 76:6].

In Arabic we say: Allah's House, Allah's slaves, and so on, are forms of honoring the object but such objects are completely separated from Allah Himself.

He Says: {And has subjected to you all that is in the heavens and all that is in the earth; it is all as a favor and kindness from Him. …} [Quran 45:13].

3) As for their speaking of a spiritual son to Allah, such a point is in fact constitutes a proof against them. In Mark's Gospel 15:39 (He said: 'Such a man was in fact a son to God'). This refers to him as a human being, and here, a son to Allah means "a good and righteous son".

Thus, Muslims deny the Godhood of Jesus depending on texts from the Bible and the word "A son to God" does not mean begot from Allah as mentioned above in the creed of trinity. Since such an expression "a son to God and children of God" is used on a large scale in their scripture to refer to one or many people, the Christians are required to believe that everyone covered in an expression must be gods or righteous people, and Jesus is one from among them. But, they believe that only Jesus is above being human and even a god.

4) The Holy Qur'an states positively, without a doubt, that the People of the Book changed and distorted their Books:

Allah Says (interpretation of meaning): {"O people of the Scripture (Jews and Christians): Why do you mix truth with falsehood and conceal the truth while you know?"} [Quran 3:71].

{O people of the Scripture (Jews and Christians)! Now has come to you Our Messenger (Muhammad, sallallaahu alaihi wa sallam,) explaining to you much of that which you used to hide from the Scripture …} [Quran 5:15].

{And verily, among them is a party who distorts the Book with their tongues (as they read), so that you may think it is from the Book, …} [Quran 3:78].

{Then woe to those who write the Book with their own hands and then say, "This is from Allah", …} [Quran 2:79].

{Among those who are Jews, there are some who displace words from (their) right places …} [Quran 4:46].

Then, how could Christian say that the Qur'an did not refer to distortion of their Scriptures?

Allah knows best.