What is the Quranic evidence that indicates that all Muslims will enter Paradise as long as they die as Muslim monotheists, irrespective of the sins they have committed?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

The creed of Ahlus-Sunnah Wal-Jamaa‘ah regarding Muslim sinners is that if any Muslim sinner dies, he is subject to the will of Allaah The Almighty: He may torture him for his sins if He wills and then admit him to Paradise, or He may forgive him. No Muslim sinners reside eternally in Hell. This was reported about the righteous predecessors by Shaykh At-Tahaawi and Shaykh Al-Islam Ibn Taymiyyah . Ahlus-Sunnah Wal-Jamaa‘ah supported their opinion with various proofs from the Quran and the Sunnah (Prophetic tradition).

The following are some of them:

1-      The Saying of Allaah The Almighty (what means): {Indeed, Allaah does not forgive association with Him, but He forgives what is less than that for whom He wills} [Quran 4:48].  Imaam As-Saffaareeni took this verse as evidence that monotheism is the greatest reason for forgiveness and a monotheist therefore achieves the greatest cause for forgiveness.

2-      The Saying of Allaah The Almighty (that means): {O you who have believed, prescribed for you is legal retribution for those murdered - the free for the free, the slave for the slave, and the female for the female. But whoever overlooks from his brother anything, then there should be a suitable follow-up and payment to him with good conduct. This is alleviation from your Lord and a mercy. But whoever transgresses after that will have a painful punishment.} [Quran 2:178].

The evidence implicit in this verse is that it called a murderer “brother,” which indicates that he is still a brother in faith although he committed this grave sin. This indicates that such major sins do not drive man out of his faith. Thus, if a person dies without repentance of the sin and is not forgiven, he will not reside eternally in Hell due to it. By the same token, scholars supported their opinion by the Saying of Allaah The Almighty (that means): {And if two factions among the believers fall in to fighting…} [Quran 49:9]. Shortly after this verse Allaah The Almighty Says (what means): {The believers are but brothers, so make settlement between your brothers. And fear Allaah that you may receive mercy.} [Quran 49:10]. Therefore, Allaah The Almighty stated that they are brothers in faith though they were fighting each other.

3-      In a Hadeeth on the authority of ‘Ubaadah ibn As-Saamit the Prophet, sallallaahu ‘alayhi wa sallam, said to his Companions, while they were giving him the oath of allegiance, that whoever fulfills his oath of allegiance will have reward from Allaah The Almighty; whoever commits a wrongdoing and receives punishment in this worldly life, this will be an expiation for him; and whoever commits a sin which Allaah The Almighty conceals, his punishment will be up to Allaah The Almighty who will punish or forgive him if he wants. [Al-Bukhari and Muslim].

4-      On the authority of Abu Sa‘eed Al-Khudri the Prophet, sallallaahu ‘alayhi wa sallam, said that after the people of Paradise enter Paradise and the people of Hell enter Hell, Allaah The Almighty will take out of Hell any person in whose heart is even the least amount of faith. [Al-Bukhari].

There are also many other proofs.

Allaah Knows best.