Disputing with the Jews and Christians About the Religion of Ibrahim
Allah censures the Jews and Christians for their dispute with Muslims over Ibrahim Al-Khalil and the claim each group made that he was one of them. Muhammad bin Ishaq bin Yasar reported that Ibn `Abbas said, "The Christians of Najran and Jewish rabbis gathered before the Messenger of Allah ﷺ and disputed in front of him. The rabbis said, `Ibrahim was certainly Jewish.' The Christians said, `Certainly, Ibrahim was Christian.' So Allah sent down,
(O people of the Scripture (Jews and Christians)! Why do you dispute about Ibrahim,) meaning, `How is it that you, Jews, claim that Ibrahim was Jew, although he lived before Allah sent down the Tawrah to Musa How is it that you, Christians, claim that Ibrahim was Christian, although Christianity came after his time" This is why Allah said,
The argumentation referred to in verse 65 was to decide whether Sayyidna Ibrahim (علیہ السلام) followed the way of the Jews, or that of the Christians. The futility of their exercise already stood exposed as both these ways in religion appeared long after the revelation of the Old and New Testaments. These just did not exist before that. How, then, could it be claimed that Sayyidna Ibrahim (علیہ السلام) . It adhered To these ways?
Verse 66 points out to the hollowness of their approach when they indulged in their argumentation on the basis of incomplete knowledge. That they would venture to do so on the basis of no knowledge could hardly he explained. The truth is that only Allah knows the way of Ibrahim (علیہ السلام) .
That way has been described in Verse 67.
Verse 68 declares that the closest of people to Sayyidna Ibrahim (علیہ السلام) were those who followed him during his time and now the closest to him is the Prophet of Islam, Muhammad a1-Mustafa ﷺ and so are the believers in him and in past prophets. These believers are the community of Muhammad ﷺ and their guardian is Allah and He will reward them for their belief.
Tazkirul Quran
Maulana Wahiduddin KhanOn ayahs 66–70
The concept of monotheism is not only a basic teaching of the Prophet Muhammad but is also enshrined as an established reality, even in the interpolated versions of the Torah and the Bible. Judged on this established criterion, Islam, unlike Judaism and Christianity, is proved to be a perfectly true religion. Monotheism implies belief in only one God. He alone should be worshipped. No one should be associated with Him. No man should be accorded that special place which is the sole prerogative of the Lord of the Universe. This concept of monotheism is preserved in its pure form only in Islam in the Quran. Other religions, while accepting monotheism ideologically, also adopted almost everything that ran counter to it. While believing in God as the Sustainer, in practice they accorded that status to their saints.
Uthmani text of the Madinah mushaf (King Fahd Complex). Translation: Saheeh International. Tafsir via Quran.com.