لَمْ يَكُنِ الَّذِينَ كَفَرُوا مِنْ أَهْلِ الْكِتَابِ وَالْمُشْرِكِينَ مُنفَكِّينَ حَتَّى تَأْتِيَهُمُ الْبَيِّنَةُ
The faithless from among the People of the Book and the polytheists were not set apart [from the community of the faithful] until the proof had come to them:
Agha Ali Puya Commentary
Commentary on Quran 98:1
[Pooya/Ali Commentary 98:1] The people of the book referred to are the Jews and the Christians who were freed from their false beliefs when the Holy Prophet, whose advent was clearly foretold in the Tawrat and the Injil, brought the final book of Allah, the Quran, in this world. See commentary of Baqarah: 40, 89, 253 for the promised prophet in the Old and New Testaments. The people of the book strayed from the true teachings of Musa and Isa and followed devious ways and false notions. The polytheists and the pagans did not believe in any scripture. When the Holy Prophet came with clear evidence (his life, his character and his teachings) to them, all of them had an opportunity to believe in Allah and follow His religion, Islam.