Loud shouts erupting from the Israelite camp strike deep terror into the Philistines, signaling that the Ark of the Covenant has arrived on the battlefield. Though they have no intention of surrendering, the Philistines are overcome with despair, haunted by the historical memory of God's ancient might [מלבי״ם, ביאור שטיינזלץ]. As they cry out in fear, they refer to God using plural terms. This reflects either the grammatical structure of the Hebrew name for God, or their own pagan habit of viewing foreign deities as multiple entities [מצודת ציון, רד״ק].
In their panic, the Philistines recall the devastating blows that struck Egypt in the wilderness. The primary approach among commentators is that this refers to the splitting of the Red Sea, a wilderness location where Pharaoh and his army met their end after enduring numerous plagues within Egypt [רש״י, מצודת דוד, רלב״ג, ביאור שטיינזלץ]. This memory highlights their realization that God's power is absolute, dominating both settled lands and barren wastelands [מלבי״ם]. Alternatively, the reference to Egypt might not mean the physical nation, but rather its spiritual guardian angel, whom God defeated at the edge of the desert [אלשיך]. Another perspective removes the geographical meaning entirely, linking the concept of the wilderness to speech. According to this view, God struck Egypt purely through His spoken command [רד״ק], or the plagues were a direct punishment for Pharaoh's arrogant words against God [חומת אנך].
The outcry within the Philistine camp is actually a mixture of two distinct reactions. The more upright individuals cry out in genuine terror, asking who can possibly save them from such a mighty God. In contrast, the wicked among them speak with mockery. They foolishly assume that God exhausted His entire supply of plagues on the Egyptians and has no punishments left. Because of this arrogance, the Philistines are later struck with a completely new and unprecedented plague of hemorrhoids [רש״י, רד״ק, אלשיך, חומת אנך].
Faced with this terrifying reality, the Philistines draw practical, tactical conclusions for the upcoming battle. Recognizing that God easily defeated the spiritual forces of Egypt, they realize it is useless to seek help from their own god, Dagon, or any other supernatural forces. Instead, they choose to fight relying strictly on natural human strength, hoping that if they do not introduce a pagan element into the conflict, God might allow the battle to play out according to the laws of nature [אלשיך]. Furthermore, keeping in mind that Pharaoh was punished for his arrogant speech, they resolve to fight bravely while taking great care not to voice any defiant words against God [חומת אנך].