إِنَّ الَّذِينَ فَرَّقُواْ دِينَهُمْ وَكَانُواْ شِيَعًا لَّسْتَ مِنْهُمْ فِى شَىْءٍ إِنَّمَآ أَمْرُهُمْ إِلَى اللَّهِ ثُمَّ يُنَبِّئُهُم بِمَا كَانُواْ يَفْعَلُونَ

“Verily, those who divide their religion and break up into sects, you have no concern with them in the least. Their affair is only with Allah, Who then will tell them what they used to do.”

[Surah Al-An’aam (6):159]

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,

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,

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,

…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,

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,
“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, You have no concern with them in the least…

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

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)

[Tafsir Ibn Kathir of the verse 6:159]