Mujahid, Qatadah, Ad-Dahhak and As-Suddi said that this Ayah was revealed about the Jews and Christians. Al-`Awfi said that Ibn `Abbas commented,

﴿إِنَّ الَّذِينَ فَرَّقُواْ دِينَهُمْ وَكَانُواْ شِيَعًا﴾

(Verily, those who divide their religion and break up into sects...) "Before Muhammad was sent, the Jews and Christians disputed and divided into sects. When Muhammad was sent, Allah revealed to him,

﴿إِنَّ الَّذِينَ فَرَّقُواْ دِينَهُمْ وَكَانُواْ شِيَعًا لَّسْتَ مِنْهُمْ فِى شَىْءٍ﴾

(Verily, those who divide their religion and break up into sects, you have no concern with them in the least.) It is apparent that this Ayah refers to all those who defy the religion of Allah, or revert from it. Allah sent His Messenger with guidance and the religion of truth so that He makes it victorious and dominant above all religions. His Law is one and does not contain any contradiction or incongruity. Therefore, those who dispute in the religion,

﴿وَكَانُواْ شِيَعاً﴾

(...and break up into sects,) religious sects, just like those who follow the various sects, desires and misguidance - then Allah has purified His Messenger from their ways. In a similar Ayah, Allah said,

﴿شَرَعَ لَكُم مِّنَ الِدِينِ مَا وَصَّى بِهِ نُوحاً وَالَّذِى أَوْحَيْنَآ إِلَيْكَ﴾

(He (Allah) has ordained for you the same religion which He ordained for Nuh, and that which We have revealed to you.)﴿42:13﴾ A Hadith reads,

«نَحْنُ مَعَاشِرُ الْأَنْبِيَاءِ أَوْلَادُ عَلَّاتٍ دِينُنَا وَاحِد»

(We, the Prophets, are half brothers but have one religion.) This, indeed, is the straight path which the Messengers have brought and which commands worshipping Allah alone without partners and adhering to the Law of the last Messenger whom Allah sent. All other paths are types of misguidance, ignorance, sheer opinion and desires; and as such, the Messengers are free from them. Allah said here,

﴿لَّسْتَ مِنْهُمْ فِى شَىْءٍ﴾

(You have no concern with them in the least...) ﴿6:159﴾. Allah's statement,

﴿إِنَّمَآ أَمْرُهُمْ إِلَى اللَّهِ ثُمَّ يُنَبِّئُهُم بِمَا كَانُواْ يَفْعَلُونَ﴾

(Their affair is only with Allah, Who then will tell them what they used to do.) is similar to His statement,

﴿إِنَّ الَّذِينَ ءَامَنُواْ وَالَّذِينَ هَادُواْ وَالصَّـبِئِينَ وَالنَّصَـرَى وَالْمَجُوسَ وَالَّذِينَ أَشْرَكُواْ إِنَّ اللَّهَ يَفْصِلُ بَيْنَهُمْ يَوْمَ الْقِيـمَةِ﴾

(Verily, those who believe, and those who are Jews, and the Sabians, and the Christians, and the Majus, and those who worship others besides Allah; truly, Allah will judge between them on the Day of Resurrection.) ﴿22:17﴾ eAllah then mentioned His kindness in His decisions and His justice on the Day of Resurrection, when He said,

﴿مَن جَآءَ بِالْحَسَنَةِ فَلَهُ عَشْرُ أَمْثَالِهَا وَمَن جَآءَ بِالسَّيِّئَةِ فَلاَ يُجْزَى إِلاَّ مِثْلَهَا وَهُمْ لاَ يُظْلَمُونَ ﴾

(160. Whoever brings a good deed shall have ten times the like thereof to his credit, and whoever brings an evil deed shall have only the recompense of the like thereof, and they will not be wronged.)