Why did Allah not despise the remnants of the People of the Book before the advent of Prophet Muhammad (peace be upon him), despite their being in error and disbelief, and why did He send down the final message to them if they were upon faith?

It is known that the sending of messengers and the revelation of messages is not conditioned on the absence of faith. The reason why Allah did not abhor the remaining People of the Book is their adherence to monotheism and their belief in what Jesus (peace be upon him) brought without distortion. Scholars have mentioned that these were a group from the people of Jesus who remained his followers until they believed in the Prophet Muhammad (peace be upon him). Allah revealed concerning them: "Indeed, those who believed and those who were Jews or Christians or Sabeans - those who believed in Allah and the Last Day and did righteousness - will have their reward with their Lord, and no fear will there be concerning them, nor will they grieve." (Al-Baqarah: 62).