قُلۡ يَـٰٓأَهۡلَ ٱلۡكِتَٰبِ لِمَ تَكۡفُرُونَ بِـَٔايَٰتِ ٱللَّهِ وَٱللَّهُ شَهِيدٌ عَلَىٰ مَا تَعۡمَلُونَ
Say (O dear Prophet Mohammed – peace and blessings be upon him), “O People given the Book(s)! Why do you not believe in the verses (or signs) of Allah, whereas your deeds are being witnessed by Allah?”
Tafsir:
Chastising the People of the Book for Their Disbelief and Blocking the Path of Allah
In this Ayah Allah criticizes the disbelieving People of the Book for refusing the truth, rejecting Allah's Ayat and hindering those who seek to believe from His path, although they know that what the Messenger was sent with is the truth from Allah. They learned this from the previous Prophets and honorable Messengers, may Allah's peace and blessings be on them all. They all brought the glad tidings and the good news of the coming of the unlettered, Arab, Hashimi Prophet from Makkah, the master of the Children of Adam, the Final Prophet and the Messenger of the Lord of heavens and earth. Allah has warned the People of the Book against this behavior, stating that He is Witness over what they do, indicating their defiance of the knowledge conveyed to them by the Prophets. They rejected, denied and refused the very Messenger whom they were ordered to convey the glad tidings about his coming. Allah states that He is never unaware of what they do, and He will hold them responsible for their actions, R
يَوْمَ لاَ يَنفَعُ مَالٌ وَلاَ بَنُونَ
(The Day whereon neither wealth nor sons will avail) 26:88.