Jonathan establishes a psychological and spiritual test to determine whether to launch an attack against the Philistines. The test relies entirely on how the enemy reacts to the sudden appearance of just two lone Israelite warriors. If the Philistines invite the two men to come up to them, it will serve as a definitive sign of victory. Such a passive reaction reveals that the fear of God has struck the enemy camp, paralyzing them with terror and leaving them afraid to move from their current position [רש״י]. Because the Philistines are facing only two individuals, a hesitant response cannot be explained by logical military strategy. Therefore, the very nature of their reaction becomes the miraculous sign [ביאור שטיינזלץ].
Beyond their hesitation, the specific words chosen by the Philistines serve as an unconscious prophecy. Their own mouths betray them, as their invitation to ascend subtly hints that Israel will ultimately rise up, overcome, and defeat them [מצודת דוד]. Upon receiving this sign, Jonathan and his armor-bearer will know with certainty that God has delivered the enemy into their hands. This clear proof is essential to give the rest of the Israelites the confidence needed to launch an offensive and pursue the enemy. It marks a complete reversal from their previous state, where they were hiding in deep fear [רלב״ג].
This proactive approach to battle also highlights a deeper spiritual principle. Even though true salvation and victory come exclusively from God, He desires that the Israelites make a physical effort and actively engage in the fight. By requiring their involvement, God creates the appearance of human achievement, doing so specifically to bestow honor upon the people of Israel [חומת אנך].