What does 1 Samuel 5:6 mean?

The Philistines had so thoroughly defeated the Israelites (1 Samuel 4:10–11) that they mistakenly believed their false god, Dagon, must be mightier than the One True God of the Israelites. They acted on this assumption by capturing the ark of the covenant (Exodus 25:10–16) and bringing it back to their temple as a trophy. But that was not an accurate view (1 Samuel 4:3). God shows the Philistines that He cannot be contained as if He were a captured enemy of war.

The Lord visually pictured His absolute superiority over the Philistines' god. They placed the ark of the covenant in Dagon's temple, but God toppled and then dismembered the statue of Dagon. Each time with the statue facing downward in front of the ark (1 Samuel 5:2–5). Thus, in the very place the false god was to be worshiped, Dagon has shown submission to the true God and been defeated before Him. The statue was thoroughly desecrated and Yahweh's contempt made clear.

Now the Lord begins to use His power against the Philistines. The phrase "the hand of the LORD," yad YHWH in Hebrew, is often used in Scripture to describe God's active judgment against someone (Exodus 9:3; Deuteronomy 2:15; Judges 2:15). In this case, the Lord's hand is heavy against the people of Ashdod and the territory surrounding the temple of Dagon where they think themselves to be holding God Himself captive.

The Lord's heavy hand causes the people to be terrified and to suffer from a physical affliction. The term used here is opālim, which can refer to boils, sores, or even hemorrhoids. This is later connected somehow to vermin (1 Samuel 6:4–5). The text is not at all clear about the exact nature of this disease. All that's clear is that it was physical, deadly, and caused tremendous levels of panic (1 Samuel 5:11). That fear, itself, seems to have led to further death and destruction (1 Samuel 5:12). A possible parallel to these events is the "Black Death" of the middle ages. That was caused by bubonic plague: a disease causing painful swollen sores, spread by fleas carried by mice and rats. It's also possible the tumors, themselves, were being described as "like mice," instead.

This plague certainly echoes those brought on the Egyptians during the time of Moses, particularly the sixth plague that caused boils (Exodus 9:8–12). In fact, the ability of Israel's "gods" to cause plagues in their enemies was exactly what the Philistines feared when they heard that the ark of the Lord had been brought to the battle (1 Samuel 4:8). Now it was happening to them.