According to search-discovered classical Islamic scholarship, Apostasy (الردة - ar-Riddah) is the willful act of a Muslim rejecting the faith of Islam after having accepted it. The Quran addresses this topic with profound seriousness, as detailed by commentators like Ibn Kathir, who explains that verse 2:217 establishes the primary spiritual consequence: the complete nullification of one's good deeds in this life and the Hereafter, resulting in eternal punishment if one dies in that state. However, this severity is consistently balanced by divine mercy. Al-Qurtubi, in his legal analysis of verses like 3:89, emphasizes that the door to repentance (Tawbah) remains open. The Quran makes a clear exception for those who sincerely repent, reform their ways, and return to faith, promising them Allah's forgiveness. Al-Tabari's linguistic analysis grounds the term in the root for 'turning back,' highlighting the conscious choice of reversal. The Quranic narrative frequently links apostasy with hypocrisy (nifaq), particularly in verses like 4:137, describing those who waver between belief and disbelief. Thus, the comprehensive Quranic theme is a stern warning against abandoning faith, coupled with a constant, merciful call to return through sincere repentance.