What does Judges 9:4 mean?

The rulers of the city of Shechem have agreed to support Abimelech. He has offered his efforts to break Shechem out from under Gideon's sons, in exchange for becoming their sole ruler. The deal has been struck: if Abimelech will wipe out the rest of Gideon's seventy sons, the leaders of Shechem will make him their king.

To help Abimelech accomplish this, they give him seventy pieces of silver from the house of Baal-berith. The massive temple to Baal-berith was in Shechem. The previous chapter ended with the sad news that the people of Israel had made Baal-berith their god in the place of Yahweh (Judges 8:33). This connection suggests that if officials from this temple made Abimelech king, he may have been considered the ruler of the entire nation.

Abimelech uses the cash to hire low-level criminal muscle. These are not the kind of professional soldiers one might normally associated with "mercenaries." Rather, Scripture depicts them as "worthless and reckless" fellows. The first word comes from a Hebrew term implying something "empty," and was often used to mean someone lacking morals or a conscience. The second term means something shallow, thoughtless, or lacking self-control. Combined, the phrase suggests the kind of easily manipulated, overly violent henchmen seen in action movies and television series. Modern English slang might call these men "goons," "hooligans," or "gangsters." Such criminals might be willing to take orders and kill people for money. That's exactly what Abimelech will use them for.