Are the People of the Book, before the advent of the Prophet, peace be upon him, considered among Ahl al-Fatrah (those who lived in a period without a prophet) who will not be punished until they are tested on the Day of Resurrection?

Before the advent of Prophet Muhammad, peace be upon him, among the People of the Book, some acted according to their scripture and did not disbelieve, while others altered their scripture and did not act upon it. Allah praised those who remained steadfast in their revealed religion, as He states: "And among the people of Moses is a community who guide by the truth and by it do justice" (Quran 7:159), and His saying: "They are not [all] alike; among the People of the Book is a community standing [in obedience], reciting the verses of Allah during periods of the night and prostrating" (Quran 3:113). The Prophet, peace be upon him, said: "Indeed, Allah looked upon the inhabitants of the earth and detested them, both Arabs and non-Arabs, except for remnants among the People of the Book." Therefore, they are not considered 'people of a void period' (ahl al-fatrah), rather the حجت (proof) is established against them by what they possess of the Scripture. So, whoever acted upon what he was commanded and did not alter anything, then lived to see Muhammad, peace be upon him, and followed him, he is saved. But whoever altered his scripture and did not act upon it, he is deserving of punishment.