The Believers among the People of the Book
Allah tells;
الَّذِينَ اتَيْنَاهُمُ الْكِتَابَ مِن قَبْلِهِ هُم بِهِ يُوْمِنُونَ
Those to whom We gave the Scripture before it, they believe in it.
Allah tells us that the pious scholars among the People of the Book believe in the Qur'an, as He says;
الَّذِينَ اتَيْنَـهُمُ الْكِتَـبَ يَتْلُونَهُ حَقَّ تِلَوَتِهِ أُوْلَـيِكَ يُوْمِنُونَ بِهِ
Those to whom We gave the Book recite it as it should be recited, they are the ones who believe therein. (2;121)
وَإِنَّ مِنْ أَهْلِ الْكِتَـبِ لَمَن يُوْمِنُ بِاللَّهِ وَمَأ أُنزِلَ إِلَيْكُمْ وَمَأ أُنزِلَ إِلَيْهِمْ خَـشِعِينَ للَّهِ
And there are, certainly, among the People of the Scripture, those who believe in Allah and in that which has been revealed to you, and in that which has been revealed to them, humbling themselves before Allah. (3;199)
قُلْ ءَامِنُواْ بِهِ أَوْ لَا تُوْمِنُواْ إِنَّ الَّذِينَ أُوتُواْ الْعِلْمَ مِن قَبْلِهِ إِذَا يُتْلَى عَلَيْهِمْ يَخِرُّونَ لِلٌّذْقَانِ سُجَّدًا
وَيَقُولُونَ سُبْحَانَ رَبِّنَأ إِن كَانَ وَعْدُ رَبِّنَا لَمَفْعُولاً
Verily, those who were given knowledge before it, when it is recited to them, fall down on their faces in humble prostration. And they say;"Glory be to our Lord! Truly, the promise of our Lord must be fulfilled." (17;107-108)
وَلَتَجِدَنَّ أَقْرَبَهُمْ مَّوَدَّةً لِّلَّذِينَ امَنُواْ الَّذِينَ قَالُوَاْ إِنَّا نَصَارَى ذَلِكَ بِأَنَّ مِنْهُمْ قِسِّيسِينَ وَرُهْبَانًا وَأَنَّهُمْ لَا يَسْتَكْبِرُونَ
وَإِذَا سَمِعُواْ مَا أُنزِلَ إِلَى الرَّسُولِ تَرَى أَعْيُنَهُمْ تَفِيضُ مِنَ الدَّمْعِ مِمَّا عَرَفُواْ مِنَ الْحَقِّ يَقُولُونَ رَبَّنَا امَنَّا فَاكْتُبْنَا مَعَ الشَّاهِدِينَ
... and you will find the nearest in love to the believers those who say;"We are Christians." That is because among them are priests and monks, and they are not proud.
And when they listen to what has been sent down to the Messenger, you see their eyes overflowing with tears because of the truth they have recognized.
They say;"Our Lord! We believe; so write us down among the witnesses." (5;82-83)
Sa`id bin Jubayr said,
"This was revealed concerning seventy priests who were sent by An-Najashi (ruler of Ethiopia). When they came to the Prophet, he recited to them;
يس
وَالْقُرْءَانِ الْحَكِيمِ
Ya Sin. By the Qur'an, full of wisdom. (36;1-2) until he completed the Surah.
They began to weep, and they embraced Islam.
These other Ayat were revealed concerning them;
الَّذِينَ اتَيْنَاهُمُ الْكِتَابَ مِن قَبْلِهِ هُم بِهِ يُوْمِنُونَ
وَإِذَا يُتْلَى عَلَيْهِمْ قَالُوا امَنَّا بِهِ إِنَّهُ الْحَقُّ مِن رَّبِّنَا إِنَّا كُنَّا مِن قَبْلِهِ مُسْلِمِينَ