דברים, פרק כ׳, פסוק י״ח

The harsh mandate to wipe out the Canaanite nations is rooted in a profound fear of cultural and religious assimilation. The presence of these nations poses an existential spiritual threat, as their pagan practices and corrupt beliefs could easily erode the morals and faith of the Israelites [ביאור שטיינזלץ]. The primary danger is not merely the temptation to worship foreign gods, an issue addressed elsewhere. Instead, there is a more subtle and equally severe risk: the Israelites might adopt the horrific rituals of these nations, such as burning children, and attempt to use those very methods to worship God. Practices considered desirable to pagan idols are an absolute abomination before God [שד״ל]. Therefore, allowing even a single individual from the Canaanite nations to remain could lead an Israelite to learn these gruesome worship methods and apply them to God, resulting in a terrible sin [רמב״ן, הטור הארוך, ביאור יש״ר].

Despite the severity of this command, a fundamental exception exists. The obligation to destroy these nations applies only as long as they cling to their corrupt ways and serve as a negative influence. If they repent, abandon their idolatry, and no longer pose a spiritual danger, it is permitted and even proper to accept them and spare their lives [רש״י, תורה תמימה, צפנת פענח, רש ר הירש].

This raises a deep discussion regarding what level of repentance is required for them to be spared. One approach suggests that simply accepting the seven universal moral laws of Noah is sufficient, without the need for a full conversion. If the requirement were full conversion, it would be obvious that their lives should be spared. Thus, the true insight is that merely abandoning idolatry and adopting basic human morality is enough to save them [מזרחי, שפתי חכמים].

Other commentators draw a distinction based on geography and timing. They argue that accepting basic moral laws only spares the nations living outside the borders of the Land of Israel. For the seven Canaanite nations living within the land, a mere declaration of basic morality is not accepted once a war has begun, out of concern that their repentance is driven solely by fear rather than genuine intent. These local nations could only be saved if they accepted the conditions of peace before the outbreak of war, much like the peace letters sent by Joshua before his battles, or through a complete and absolute conversion [העמק דבר, יריעות שלמה, אדרת אליהו, תורה תמימה].