Say: "O People of the Scripture! You have nothing till you act according to the Tawrah, the Injil, and what has (now) been sent down to you from your Lord (the Qur'an)." Verily, the revelation that has come to you from your Lord makes many of them increase in rebellion and disbelief. So do not grieve for the people who disbelieve (68)Surely, those who believe, and those who are the Jews and the Sabians and the Christians, whosoever believed in Allah and the Last Day, and worked righteousness, on them shall be no fear, nor shall they grieve (69)
There is no Salvation Except through Faith in the Qur'an
Allah says: O Muhammad, say,
يَا أَهْلَ الْكِتَابِ لَسْتُمْ عَلَىٰ شَيْءٍ
(O People of the Scripture! You have nothing...) meaning no real religion until you adhere to and implement the Tawrah and the Injil. That is, until you believe in all the Books that you have that Allah revealed to the Prophets. These Books command following Muhammad ﷺ and believing in his prophecy, all the while adhering to his Law. Before, we explained Allah's statement,
وَلَيَزِيدَنَّ كَثِيرًا مِّنْهُم مَّا أُنزِلَ إِلَيْكَ مِن رَّبِّكَ طُغْيَانًا وَكُفْرًا
(Verily, the revelation that has come to you from your Lord makes many of them increase in rebellion and disbelief.)
فَلَا تَأْسَ عَلَى الْقَوْمِ الْكَافِرِينَ
(So do not grieve for the people who disbelieve), Do not be sad or taken aback by their disbelief. Allah said next,
إِنَّ الَّذِينَ آمَنُوا
(Surely, those who believe) referring to Muslims,
وَالَّذِينَ هَادُوا
(those who are the Jews) who were entrusted with the Tawrah,
وَالصَّابِئُونَ
(and the Sabians...) a sect from the Christians and Magians who did not follow any particular religion, as Mujahid stated. As for the Christians, they are known and were entrusted with the Injil. The meaning here is that if each of these groups believed in Allah and the Hereafter, which is the Day of Judgement and Reckoning, and performed good actions, which to be so, must conform to Muhammad's Law, after Muhammad ﷺ was sent to all mankind and the Jinns. If any of these groups held these beliefs, then they shall have no fear of what will come or sadness regarding what they lost, nor will grief ever affect them. We discussed a similar Ayah before in Surat Al-Baqarah [2:62].