Islam teaches that salvation requires genuine faith (īmān) combined with righteous deeds (ʿamal ṣāliḥ), and ultimately depends on Allah's mercy. No one enters Paradise solely on the basis of faith alone — deeds must accompany it. But at the end, even those who deserve punishment may be admitted by Allah's mercy.
"Successful indeed are the believers — those who humble themselves in their prayer, who avoid idleness, who give zakāh, who guard their privates, except from their wives or those their right hands possess, for indeed they are not to be blamed — but whoever seeks beyond that, then those are the transgressors — and those who are trustworthy in their trusts and their covenants, and those who are earnest in their work, and those who refrain from adultery — whoever does that will get his recompense punished with the Hellfire; but those who do not find forgiveness from that — for them will be a soft way. And indeed, We have made the Qur'an easy for remembrance, so is there any who will remember?"
— Quran 23:1–9 (Sūrat al-Muʾminūn, The Believers) — Summary of success criteria
"So whoever does an atom's weight of good will see it, and whoever does an atom's weight of evil will see it."
— Quran 99:7–8 (Sūrat al-Zalzalah, The Earthquake)
"Indeed, those who have believed and done righteous deeds — they will have Gardens of Paradise as a lodging, wherein they abide forever."
— Quran 18:107–108 (Sūrat al-Kahf, The Cave)
"And whomsoever Allah wants to guide, He makes his breast wide for Islam; and whomsoever He wants to misguide, He makes his breast strait and confined as though he were climbing up into the sky."
— Quran 6:125 (Sūrat al-Anʿām, The Cattle)
"Say, 'O My servants who have transgressed against themselves [by sinning], do not despair of the mercy of Allah. Indeed, Allah forgives all sins. Indeed, it is He who is the Forgiving, the Merciful.'"
— Quran 39:53 (Sūrat az-Zumar, The Troops)
"And We have not sent you [O Muhammad] except as a mercy to the worlds."
— Quran 21:107 (Sūrat al-Anbiyāʾ, The Prophets)
The Islamic position is nuanced: salvation is earned through faith and works (the scale/mīzān will weigh deeds on Judgment Day), but Allah's mercy is the final determinant. A person may enter Paradise despite their sins if Allah wills mercy over them — but this is earned by Allah's justice first, then mercy.
Christianity teaches that salvation is by grace through faith alone, apart from works. No amount of good deeds can earn salvation — it is a free gift from God, made possible by Christ's atoning death and resurrection. Works are the result of salvation, not the means to it.
"For by grace you have been saved through faith. And this is not your own doing; it is the gift of God, not a result of works, so that no one may boast."
— Ephesians 2:8–9 (ESV) — Letter of Paul to the Ephesians
"For all have sinned and fall short of the glory of God, and are justified by his grace as a gift, through the redemption that is in Christ Jesus."
— Romans 3:23–24 (ESV) — Letter of Paul to the Romans
"For God so loved the world, that he gave his only Son, that whoever believes in him should not perish but have eternal life."
— John 3:16 (ESV) — Gospel of John (c. 90–120 CE)
"He saved us, not because of works done by us in righteousness, but according to his own mercy, by the washing of regeneration and renewal of the Holy Spirit."
— Titus 3:5 (ESV) — Letter of Paul to Titus
"Because if you confess with your mouth that Jesus is Lord and believe in your heart that God raised him from the dead, you will be saved."
— Romans 10:9 (ESV)
The Apostle Paul's theology of salvation by grace through faith is the dominant thread across the New Testament. The Reformers (Luther, Calvin) made this the central doctrine of the Protestant Reformation: sola gratia (grace alone), sola fide (faith alone), solus Christus (Christ alone).