Commentators explain that Amalek's attack was not just an act of war but a profound sin against God. As relatives of Israel (descendants of Esau), they knew of God's power and covenant. Their unprovoked, treacherous attack on the weak and weary was seen as a deliberate rebellion against God's plan, stemming from what John Calvin calls "sacrilegious jealousy." Their core sin, as Calvin notes, was that they "feared not God."