What does Judges 15:20 mean?

The writer of Judges ends both this section and the following section about Samson's life by saying that he judged (Judges 2:16–19) for twenty years during the era of the Philistines. Despite selfishness, lust, and arrogance, Samson was God's instrument during this time in Israel's history. The Lord's purpose for him was to be an agent of disruption, shattering the Philistine's sense of comfortable control over Israel (Judges 14:4). Each "judge" of Israel had a different type of service, and Scripture doesn't hint at what Samson did during his tenure, other than the events explicitly recorded.

Samson's term as a judge did not end with Israel's freedom from oppression under the Philistines. His role was only to "begin" that process (Judges 13:5). During this time, approximately 1069–1049 BC, Israel grew stronger, but did not break out from under their enemies. Those who came later—such as the judge and prophet Samuel (1 Samuel 7:11–14)—would finish the job.

The following chapter shows that Samson never overcame his moral failures. Whatever he learned from his vendetta against the Philistines didn't dampen his weakness for women, or make him more resistant to their manipulations. This makes him one of the most frustratingly complicated figures in the entire Bible. There is no doubt his life was marred by sin and stupid decisions, yet there is likewise no doubt that he served to further God's will in that moment.