Not addressing Christianity...
But they have attributed to Allah partners - the jinn, while He has created them - and have fabricated for Him sons and daughters without knowledge. Exalted is He and high above what they describe. [He is] Originator of the heavens and the earth. How could He have a son when He does not have a companion and He created all things? And He is, of all things, Knowing. (6:100-101)
Salaam Alaikum. I looked at the tafsir of surahs 6:100-101 by Ibn Abbas, and in fact he claims that this is a reference to Christians and Jews. Ibn Jalayn claims it is a reference to Jews. Ibn Kathir claims it is a reference to Christians and Jews.
Muhammad here I think misunderstood the meaning of the term Son of God, for both how Christians see Jesus and sons and daughters of God for how Christians and Jews see people who choose to follow God.
Ibn Abbas
(Yet they ascribe as partners unto Him the jinn) they said: Allah, Exalted is He, and Satan are brothers and partners: Allah is the Creator of human beings, beasts and cattle while Satan is the Creator of snakes, scorpions and predatory beasts. This is the claim of the Magians, (although He did create them) and command them to declare His divine Oneness, (and impute falsely, without knowledge) without knowledge, argument or proof, (sons) as claimed by the Jews and Christians (and daughters unto Him) among the angels and idols, as claimed by the Arab idolaters. (Glorified be He) He has exonerated Himself from having children or partners (and high exalted) and He absolves Himself (above (all) that they ascribe (unto Him)) of sons and daughters.
(The Originator) the Creator (of the heavens and the earth!) He created them when they were nothing before such creation. (How can He have a child, when there is for Him no consort) no wife, (when He created all things and is Aware of all things) of all created beings?
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Ibn Jalalayn
Yet they ascribe to God (liLlāhi, the indirect object) as associates (shurakāa, the direct object, which is substituted by [the following, al-jinn]) the jinn, since they obey them by worshipping graven images, even though He created them: so how can they be associates? And they falsely impute to Him (read kharaqū or kharraqū
, that is, they invent, sons and daughters without any knowledge, saying, Ezra (Uzayr) is the son of God, and the angels are the daughters of God. Glory be to Him an affirmation of His transcendence and exalted be He above what they describe!, of Him having a child.
He is, the Originator of the heavens and the earth, which He originated uniquely without precedent; how should He have a son, when He has no consort, spouse, and He created everything, that was meant to be created, and He has knowledge of all things?
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Tafsir Ibn Kathir
This Ayah refutes the idolators who worshipped others besides Allah and associated the Jinns with Him in worship. Glory be to Allah above this Shirk and Kufr. If someone asks, how did the idolators worship the Jinns, although they only were idol worshippers The answer is that in fact, they worshipped the idols by obeying the Jinns who commanded them to do so. Allah said in other Ayat,
﴿إِن يَدْعُونَ مِن دُونِهِ إِلاَّ إِنَـثاً وَإِن يَدْعُونَ إِلاَّ شَيْطَـناً مَّرِيداً - لَّعَنَهُ اللَّهُ وَقَالَ لاّتَّخِذَنَّ مِنْ عِبَادِكَ نَصِيباً مَّفْرُوضاً - وَلأضِلَّنَّهُمْ وَلأُمَنِّيَنَّهُمْ وَلاّمُرَنَّهُمْ فَلَيُبَتِّكُنَّ ءَاذَانَ الاٌّنْعَـمِ وَلاّمُرَنَّهُمْ فَلَيُغَيِّرُنَّ خَلْقَ اللَّهِ وَمَن يَتَّخِذِ الشَّيْطَـنَ وَلِيّاً مِّن دُونِ اللَّهِ فَقَدْ خَسِرَ خُسْرَاناً مُّبِيناً - يَعِدُهُمْ وَيُمَنِّيهِمْ وَمَا يَعِدُهُمْ الشَّيْطَـنُ إِلاَّ غُرُوراً ﴾
(They invoke nothing but female deities besides Him, and they invoke nothing but Shaytan, a persistent rebel! Allah cursed him. And he ﴿Shaytan﴾ said: "I will take an appointed portion of your servants. Verily, I will mislead them, and surely, I will arouse in them false desires; and certainly, I will order them to slit the ears of cattle, and indeed I will order them to change the nature created by Allah.'' And whoever takes Shaytan as a protector instead of Allah, has surely suffered a manifest loss. He ﴿Shaytan﴾ makes promises to them, and arouses in them false desires; and Shaytan's promises are nothing but deceptions. ) ﴿4:117-120﴾ and,
﴿أَفَتَتَّخِذُونَهُ وَذُرِّيَّتَهُ أَوْلِيَآءَ مِن دُونِى﴾
(Will you then take him (Iblis) and his offspring as protectors and helpers rather than Me) ﴿18:50﴾ Ibrahim said to his father,
﴿يأَبَتِ لاَ تَعْبُدِ الشَّيْطَـنَ إِنَّ الشَّيْطَـنَ كَانَ لِلرَّحْمَـنِ عَصِيّاً ﴾
("O my father! Worship not Shaytan. Verily! Shaytan has been a rebel against the Most Beneficent (Allah).'') ﴿19:44﴾ Allah said,
﴿أَلَمْ أَعْهَدْ إِلَيْكُمْ يبَنِى ءَادَمَ أَن لاَّ تَعْبُدُواْ الشَّيطَـنَ إِنَّهُ لَكُمْ عَدُوٌّ مُّبِينٌ - وَأَنِ اعْبُدُونِى هَـذَا صِرَطٌ مُّسْتَقِيمٌ ﴾
(Did I not ordain for you, O Children of Adam, that you should not worship Shaytan. Verily, he is a plain enemy to you. And that you should worship Me. That is a straight path.) ﴿36:60-61﴾ On the Day of Resurrection, the angels will proclaim,
﴿سُبْحَـنَكَ أَنتَ وَلِيُّنَا مِن دُونِهِمْ بَلْ كَانُواْ يَعْبُدُونَ الْجِنَّ أَكْـثَرُهُم بِهِم مُّؤْمِنُونَ﴾
(Glorified be You! You are our Protector instead of them. Nay, but they used to worship the Jinn; most of them were believers in them.) ﴿34:41﴾ This is why Allah said here,
﴿وَجَعَلُواْ للَّهِ شُرَكَآءَ الْجِنَّ وَخَلَقَهُمْ﴾
(Yet, they join the Jinns as partners in worship with Allah, though He has created them.) ﴿6:100﴾, Alone without partners. Consequently, how is it that another deity is being worshipped along with Him As Ibrahim said,
﴿قَالَ أَتَعْبُدُونَ مَا تَنْحِتُونَ - وَاللَّهُ خَلَقَكُمْ وَمَا تَعْمَلُونَ ﴾
("Worship you that which you (yourselves) carve While Allah has created you and what you make!'') ﴿37:95-96﴾ Allah alone is the Creator without partners. Therefore, He Alone deserves to be worshipped without partners. Allah said next,
﴿وَخَرَقُواْ لَهُ بَنِينَ وَبَنَاتٍ بِغَيْرِ عِلْمٍ﴾
(And they Kharaqu (attribute falsely) without knowledge, sons and daughters to Him.)
Allah mentions the misguidance of those who were led astray and claimed a son or offspring for Him, as the Jews did with `Uzayr, the Christians with `Isa and the Arab pagans with the angels whom they claimed were Allah's daughters. Allah is far holier than what the unjust, polytheist people associate with Him. The word, Kharaqu, means `falsely attributed, invented, claimed and lied', according to the scholars of the Salaf. Allah's statement next,
﴿سُبْحَـنَهُ وَتَعَـلَى عَمَّا يَصِفُونَ﴾
(Be He Glorified and Exalted above (all) that they attribute to Him.) means, He is holier than, hallowed, and Exalted above the sons, rivals, equals and partners that these ignorant, misled people attribute to Him.
﴿بَدِيعُ السَّمَـوَتِ وَالاٌّرْضِ أَنَّى يَكُونُ لَهُ وَلَدٌ وَلَمْ تَكُنْ لَّهُ صَـحِبَةٌ وَخَلَقَ كُلَّ شَىْءٍ وهُوَ بِكُلِّ شَىْءٍ عَلِيمٌ ﴾
(101. He is the Badi` (Originator) of the heavens and the earth. How can He have children when He has no wife He created all things and He is the All-Knower of everything.)
(He is the Badi` of the heavens and the earth) Meaning He originated, created, invented and brought them into existence without precedence, as Mujahid and As-Suddi said. This is why the word for innovation - Bid`ah - comes from it, because it is something that did not have a precedence.
﴿أَنَّى يَكُونُ لَهُ وَلَدٌ وَلَمْ تَكُنْ لَّهُ صَـحِبَةٌ﴾
(How can He have children when He has no wife) for the child is the offspring of two compatible spouses. Allah does not have an equal, none of His creatures are similar to Him, for He alone created the entire creation. Allah said;
﴿وَقَالُواْ اتَّخَذَ الرَّحْمَـنُ وَلَداً - لَقَدْ جِئْتُمْ شَيْئاً إِدّاً ﴾
(And they say: "The Most Beneficent (Allah) has begotten a son.'' Indeed you have brought forth (said) a terrible evil thing.) ﴿19:88-89﴾, until,
﴿وَكُلُّهُمْ ءَاتِيهِ يَوْمَ الْقِيَـمَةِ فَرْداً ﴾
(And everyone of them will come to Him alone on the Day of Resurrection.)﴿19:95﴾.
﴿وَخَلَقَ كُلَّ شَىْءٍ وهُوَ بِكُلِّ شَىْءٍ عَلِيمٌ﴾
(He created all things and He is the All-Knower of everything.) He has created everything and He is All-Knower of all things. How can He have a wife from His creation who is suitable for His majesty, when there is none like Him How can He have a child then Verily, Allah is Glorified above having a son.
﴿ذلِكُمُ اللَّهُ رَبُّكُمْ لا إِلَـهَ إِلاَّ هُوَ خَـلِقُ كُلِّ شَىْءٍ فَاعْبُدُوهُ وَهُوَ عَلَى كُلِّ شَىْءٍ وَكِيلٌ - لاَّ تُدْرِكُهُ الاٌّبْصَـرُ وَهُوَ يُدْرِكُ الاٌّبْصَـرَ وَهُوَ اللَّطِيفُ الْخَبِيرُ ﴾
(102. Such is Allah, your Lord! None has the right to be worshipped but He, the Creator of all things. So worship Him (alone), and He is the Guardian over all things.) (103. No vision can grasp Him, but His grasp is over all vision. He is the Most Subtle, Well-Acquainted (with all things).)
Tafsir Ibn Kathir - Quran Tafsir - Rebuking the Idolators