What does 1 Samuel 6:3 mean?

Most everyone among the Philistines was convinced of the need to get the ark of the Lord (Exodus 25:10–16) out of their territory and to send it back to the Israelites (1 Samuel 6:2). They understood that to be their only hope of stopping the plague of tumors and the panic that came with it (1 Samuel 5:6–12). They also believed it mattered how they returned the ark to Israel. They consulted with their own priests and diviners to make sure they did not send it back in a way that made Israel's God even angrier than He already was.

The priests and diviners decide it would be a terrible offense to send the ark back without an offering of some kind. It seems to be standard behavior to send gifts to those we are seeking to appease. For example, Jacob sent gifts to Esau to prevent what he expected was an impending attack (Genesis 32). Abigail sent gifts to David to placate him when he was prepared to destroy Nabal's household (1 Samuel 25). The Philistines appear to have known at least a version of the story of Moses and the plagues God sent on Egypt (1 Samuel 4:8; 6:6). Per God's instructions the Israelites had asked the Egyptians for gold, silver, and clothing before the Passover, and the Egyptians obliged (Exodus 11:2; 12:35). After the deaths of the firstborn, the Egyptians urged the people to leave quickly, and the Israelites took those gifts with them (Exodus 12:33–36). The priests seem to base their logic for their proposed offerings on their understanding of God's interactions with Egypt (1 Samuel 6:6). Whether because of this, their understanding of gods and offerings, or common relational norms, the priests agree that the Philistines should return the ark with a gift.

The priests call this a guilt offering. They seem to understand it as some form of payment to the Lord for their disrespect toward Him and His ark. They believe that if they send this guilt offering, the God of Israel will heal their people from the terrible plague. If He does, the priests add, then they will know for sure that the Lord's anger at their possession of the ark was the reason for His judgment on them.