‘ And the children of Dan set up for themselves the graven image, and Jonathan the son of Gershom, the son of Moses, he and his sons were priests to the tribe of the Danites until the day of the captivity of the land. And they set up for themselves Micah's graven image, which he made, all the time that the house of God was in Shiloh.'
Presumably Dan built a house of God or erected a Tabernacle and in it they set up the graven image. This demonstrates that the graven image was the central object. Thus, as suggested at the beginning (Judges 17:3), it may well have been a miniature replica of the Ark of the Covenant, the throne of Yahweh, with the covering cherubim.
It was set up ‘all the time that the house of God was at Shiloh'. This suggests that this sub-tribe of Dan did not see themselves at that time as still part of the tribal confederacy. Rather they worshipped at their own rival sanctuary. These were the depths to which they had sunk. They were no longer part of the covenant. It may be that this reference to Shiloh signifies that they did later return to the covenant and loyalty to the central sanctuary after Samuel's great victory over the Philistines. Certainly they were later a part of Israel.
“Jonathan the son of Gershom, the son of Moses, he and his sons were priests to the tribe of the Danites until the day of the captivity of the land.” We probably learn here who the Levite was who had been installed as priest by Micah. His name was Jonathan and he claimed direct descent from Moses. In view of the shortness of the time that had passed this could probably be verified. Thus the Danite sanctuary claimed Moses as the source of their priesthood. It was a sad reflection on the state of things when a descendant of Moses could behave as he had done, setting up as a priest, contrary to the Law of Moses, aiding the theft of the religious objects, and deserting his patron.
“Son of Gershom” means ‘descended from Gershom' in accordance with ancient usage. He may not have been directly his son, possibly his grandson or great grandson, for this was early in the Judges period. Compare how Phinehas, Aaron's grandson, seems to have been still living (Judges 20:28) around this time. But he was not a young man.
“Until the day of the captivity of the land.” This probably refers to the Philistine invasion when the house of God at Shiloh ceased (1 Samuel 4 see Jeremiah 7:12) and the Philistines for a time controlled large parts of Israel west of Jordan. If this is so it confirms the idea that they at that stage, or not long afterwards, rejoined the tribal confederacy.
Other suggestions have been the destruction of the north by Tiglath Pileser around 734 BC (2 Kings 15:20) or the Assyrian invasion which resulted in the capture of Samaria in c. 721 BC. But this is unlikely. It is very questionable whether David would have allowed the Sanctuary to continue, for the sake of unification if nothing else, once he established Jerusalem as the central sanctuary, and even less so Solomon in his early years, although it may be that it would have been allowed to continue as a local sanctuary. And it is clear that Dan did again become a part of the tribal confederacy for it featured as part of Jeroboam's kingdom when Israel split from Judah.
The setting up in Dan of a sanctuary by Jeroboam when Israel split from Judah (1 Kings 12:29-30) may have been the taking over, and improvement, of this sanctuary. That may then explain the reference to the captivity of the land as relating to the end of the sanctuary as relating to the one continued and improved by Jeroboam. (The comment about the captivity of the land would then be an interpolated note). But it is far more likely that the reference was to the time when they returned to the covenant.
“All the time that the house of God was in Shiloh.” The Philistine invasion and capture of the Ark would signal the end of Shiloh as the central sanctuary, combined with the death of Eli, the judge of Israel and priest of the Tabernacle (1 Samuel 4:12-18). After the Ark was later returned it was in Kiriath-jearim for twenty years (1 Samuel 7:1), with Eleazar, the son of Abinadab, as priest. But eventually, after Samuel's great victories over the Philistines, the Tabernacle and the central sanctuary, together with the Ark, were established at Nob (1 Samuel 21:1). This may have been when Dan rejoined the covenant.
So the chapter ends with the setting up of a rival to the central sanctuary, the withdrawal of a sub-tribe from the covenant, the establishment of an official priesthood not descended from the Aaronic priesthood, and all based on theft and disloyalty. Truly there was no King in Israel. It did not bode well for the future of Israel or the tribal confederacy.