An invading army often uses psychological warfare to break the spirit of its enemies before a single weapon is drawn. Standing before the walls of Jerusalem, the spokesman for the King of Assyria attempts to shatter the residents' trust in God. His central argument is that relying on God for salvation is entirely pointless, claiming that God Himself commanded the Assyrian empire to attack and ruin the land [רלב״ג]. By rhetorically asking whether he could have possibly waged this war without God's explicit permission and decree [רש״י, מצודת דוד, ביאור שטיינזלץ], his clear goal is to strike deep terror and despair into the hearts of those listening [רד״ק].
Commentators offer several explanations for how the Assyrian spokesman reached the conclusion that he was on a divine mission. One approach suggests he was familiar with the prophecies of Isaiah, perhaps even being an apostate Jew who knew the prophetic writings intimately [רש״י, רד״ק]. Isaiah had indeed prophesied that God would bring the Assyrian king against the land. However, the spokesman critically misunderstood the message. While the prophecy foretold the fall of Samaria, he mistakenly assumed that Jerusalem was doomed to the exact same fate [מצודת דוד].
Another perspective traces his confidence directly to his overwhelming military success. Having conquered numerous nations without facing any real resistance, he naturally concluded that all his victories, including the current campaign in the Land of Israel, were granted to Him directly by God [רד״ק]. A third explanation views his claim through the lens of ancient military customs. Kings of that era routinely used divination and cast lots to discover the will of a region's local deity. Through these rituals, the spokesman likely believed he had uncovered God's approval for his mission [ביאור שטיינזלץ].
Yet, even with his bold declaration that God spoke to him, his message contains a crucial fabrication. While he asserts that he was sent on this campaign, the specific threat to completely destroy the land is his own personal addition. God never explicitly commanded him to bring about such total destruction [רש״י].