Tafsir of Al-Kafiroun 109:6

"To you your religion" is, according to the majority, a confirmation of His, the Exalted’s, saying: "I do not worship what you worship," and His saying: "Nor are you worshippers of what I worship." Likewise, His saying: "And to me [is] my religion" is, in their view, a confirmation of His saying: "Nor will I be a worshipper of what you worship." The meaning is: Your religion, which is polytheism, is confined to being yours; it does not extend to being mine, as you hope. Therefore, do not attach your empty wishes to it, for that is an impossibility. My religion, which is monotheism, is confined to being mine; it does not extend to being yours, because Allah, the Exalted, has set a seal upon your hearts due to your poor disposition, or because you have attached it to an impossibility—namely, my worship of your gods or my approval of them—or because what you promised is the very essence of polytheism. Since their intent was for both parties to share in both forms of worship, the restriction derived from placing the predicate first is inevitably a restriction of isolation (qasr ifrad). It is also permissible that this is a confirmation of His saying: "Nor will I be a worshipper of what you worship." According to what has been mentioned, the verse is definitive (muhkam) and not abrogated, as is not hidden.

Alternatively, the intent may be the cessation of hostility, in the sense: I am a Prophet sent to you to call you to the Truth and to salvation. If you do not accept from me and do not follow me, then leave me be, and do not call me to polytheism. In this view, as many have stated, it is abrogated by the Verse of the Sword.

"Religion" (al-din) has also been interpreted as "reckoning" (al-hisab), meaning: to you is your reckoning, and to me is my reckoning; no trace of the other’s deeds returns to either of us. It has also been interpreted as "recompense" (al-jaza’), meaning: to you is your recompense, and to me is my recompense. It is said that the speech, under both interpretations, is an expository initiation, as if it were said: "What will happen if we persist in the worship of our gods, and you persist in the worship of your God?" Thus, it was said: "To you [is your religion]...," meaning they shall have evil, and he—upon him be peace—shall have good. However, the lam (particle of possession) was used in "to you" (lakum) for the sake of symmetry (mushakalah); according to this, there is also no abrogation. It is possible that the intent is something else that would render the verse abrogated, and this is perhaps not hidden.

Sometimes "religion" is interpreted as "state" (al-hal), as it is one of its meanings, according to what al-Qali mentioned in his Amali and others. This means: to you is your state, which is befitting you—necessitated by your poor disposition—and to me is my state, which is befitting me—necessitated by my good disposition. In this case, the sentence acts as a justification for what the preceding speech contained, so there is no abrogation. It is preferable to interpret it in a way that it is not abrogated, because abrogation is contrary to the apparent meaning and should not be resorted to except in case of necessity.

Imam al-Razi presented various aspects in its interpretation, some of which are not free from scrutiny. May mercy be upon him, he mentioned that it is common practice for people to cite this verse when breaking off relations, and that this is not permissible because the Quran was not revealed to be cited in such a manner, but to be guided by. In this there is an inclination toward closing the door of iqtibas (quoting or adapting Quranic phrases into speech). The correct view is that it is permissible, for it has occurred in the speech of the Prophet—upon him be peace—and the speech of many of the Companions, the Imams, and the Followers. Al-Jalal al-Suyuti has a comprehensive and sufficient treatise on removing the confusion regarding the permissibility of iqtibas. The argument mentioned [by al-Razi] is more evident than needing to point out its weakness.

Salam and Ya’qub read "my religion" (dini) with a ya in both connection and pause, while the seven reciters omitted it. And Allah, the Exalted, knows best.