New Defender's Study Bible Notes
21:3 one tribe lacking. The enormity of what was happening suddenly dawned on the victorious tribes. The entire population of one tribe, except for six hundred men (Judges 20:47) had been wiped out, and finally the eleven tribes “repented them for Benjamin their brother” (Judges 21:6). However, they had all taken an oath not to allow any of their daughters to marry a man of Benjamin (Judges 21:18), so it seemed the tribe would soon become extinct. The drastic solution (slaying all the inhabitants of the one city in Gad that had not joined with them in the battle, except for four hundred virgins, and then allowing the other two hundred Benjamites each to capture a maid of Shiloh–Judges 21:12,21) served the purpose of keeping the tribe viable, but there is no implication that the method was the way God would have led them if they had only asked.
21:25 right in his own eyes. This tragic indictment, first lodged at Judges 17:6, is repeated in this final verse of the book. In between, in Judges 17–21, is found the most appalling description of moral and spiritual chaos that one can encounter anywhere. Yet these people were the chosen people of God, and were no more than one generation away from Joshua and “the elders that outlived Joshua, who had seen all the great works of the LORD, that He did for Israel” (Judges 2:7). Their fathers had served the Lord during that period, but then “there arose another generation after them” who “did evil in the sight of the LORD, and served Baalim” (Judges 2:10,11). It is highly probable that it was during this generation that the tragic events of Judges 17–21 took place (see notes on Judges 18:1 and 20:28). When the younger generation forsakes the faith of their fathers and begins to compromise with the pantheistic cultures of their ungodly neighbors, it may not be long before they descend into utter wickedness (see Romans 1:21-32). Almost the same thing is happening to the current generation in America and other “Christian” nations today.