So here’s how the kingdom falls apart.
Wise, experienced advisors tell Solomon’s son Rehoboam, to be a compassionate, generous leader. His crew of dude bros’ tell him to be a nastier badass than his dad. He goes with the latter, causing all of Israel to leave except Judah, his own tribe, and the tribe of Benjamin.
God appears, to avert civil war. He speaks through a man of God. And they listen.
The rest of the tribes follow jeroboam, who emerges from Egypt ready to lead the secession. They have no access to the temple at Jerusalem, and jeroboam sets up a version of the golden calf religion from exodus, with priests not from the levites tribe. He sets up two locations where they sacrifice to golden calves, which jeroboam describes as the Gods who bought them out of Egypt.
In exodus, Moses had to bring God’s judgement to many followers of the calf. Now, God’s will is to let it go, at least, his judgement will not come via a civil war for now.
Kings is history, there is very little theological commentary as it goes through. I’m just describing the sweep of it for now. The lessons are sad, and not in chapter sized chunks.
Needless to say the massive step backwards in obedience to Jehovah of the bulk of the people to the low point of the exodus story is the end of the idea that the chosen people’s society would be the model of God’s salvation.