Qur'an 53:32 — 'Those who avoid the major sins and immoralities, only [committing] slight ones. Indeed, your Lord is vast in forgiveness. He was most knowing of you when He produced you from the earth and when you were fetuses in the wombs of your mothers. So do not claim yourselves to be pure; He is most knowing of who fears Him.'

The underlying theological point about classical Islam should be represented accurately, not caricatured: mainstream Sunni theology (Ash'ari and Maturidi alike) genuinely does not offer confident assurance of salvation in this life. Final judgment is understood as pending Allah's weighing of deeds on the Mizan, and the standard spiritual posture commended by scholars like al-Ghazali (Ihya' 'Ulum al-Din, the books on fear, khawf, and hope, raja') is one of holding fear and hope in balance until death. Even the Prophet Muhammad is reported to have said, 'None of you will enter Paradise by his deeds alone,' and when asked, 'Not even you, O Messenger of Allah?' replied, 'Not even me, unless Allah covers me with His mercy' (Sahih al-Bukhari 5673; Sahih Muslim 2816). This is a coherent, deliberate feature of the classical system, not an oversight, and 53:32's warning against self-declared purity fits that system consistently. The Christian doctrine of assurance is not, however, the mirror-image error 53:32 warns against, and the comparison only works if that distinction is made. 53:32 condemns confidence grounded in *one's own* purity — self-certification of righteousness based on one's own deeds, which would indeed be presumptuous. The New Testament doctrine of assurance is explicitly not that: it is confidence grounded in an *alien* or imputed righteousness, located outside the believer, in the completed, historical work of another. Paul states the logic directly: 'God made him who knew no sin to be sin for us, so that in him we might become the righteousness of God' (2 Cor 5:21) and 'by grace you have been saved through faith... not a result of works, so that no one may boast' (Eph 2:8-9). Assurance under this framework ('there is therefore now no condemnation for those who are in Christ Jesus,' Rom 8:1; 'these things I have written to you... so that you may know that you have eternal life,' 1 John 5:13) is structurally not self-assessment of one's own moral sufficiency; it is trust that someone else's finished righteousness has been credited, which is a different kind of claim than 'I am pure.'

The New Testament grounds assurance in an objective, completed, historical event — the cross and resurrection (1 Cor 15) — plus a present pledge, the sealing of the Holy Spirit described as a down payment guaranteeing the inheritance (2 Cor 1:22; Eph 1:13-14). Assurance is thus anchored outside the fluctuating self being judged, in something already accomplished and something already given, not in an ongoing, uncompleted tally of the believer's own deeds. This is not novel to the Reformation, though Luther gave it its sharpest label (iustitia aliena, 'alien righteousness'); the logic is already patristic — the second-century Epistle to Diognetus (ch. 9) describes the 'sweet exchange' in which Christ's righteousness covers the sinner's unrighteousness.