In this chapter, Hezekiah becomes king and restores temple worship.
In short, this chapter is all about reversing the damage and neglect inflicted upon the temple by Ahaz. Verses 3-5 give a summary of Hezekiah's activity, which is repairing the temple and consecrating it (i.e. removing unclean things, or just cleaning it up in general). We know from the life of Ahaz (Hezekiah's father) that the temple was abandoned because Ahaz was a worshiper of Baal (2 Chron 28:2, 24). While Ahaz shut the doors of the temple, Hezekiah reopens them (v. 3). We can also infer that many ceremonially unclean things were stored in the temple, and Hezekiah had them removed.
This chapter has two central elements. The first is the consecration of the temple (v. 5-19) and the second is the restoration of animal sacrifice in the temple complex (v. 20-36). These actions are related because as part of the ceremonial code, a sacred offering cannot be made on a defiled altar. Therefore the temple needed to be consecrated before any offerings could be properly made there.
What stands out to me the most about Hezekiah in this chapter is the immediacy of his action. It says that in the very first month of his reign he went to reopen the temple. This was possibly his top priority. It's as if we elected a new president, and then right after inauguration they gathered their top officials to go out and build a new church or something. Obviously there are a lot of differences between modern life and ancient Judah, but even in ancient Judah the king would have had a lot of military, political and economic responsibilities. For him to go out to the temple so early in his reign is a clear statement of priorities given how many other things he could be doing.
My commentary in the previous chapter discussed a lot of the social and political upheaval in this time period, so I won't repeat that information now. Instead, I want to focus on the more human aspect which is Hezekiah himself. I have only one question that has bothered me for years: how on earth did a father like Ahaz have a son like Hezekiah? The biblical narrative is deeply critical of Ahaz, yet it is strongly favorable toward Hezekiah, because these two men are almost exactly opposite in their attitudes towards the LORD. What I want to know is how a godless Baal-worshiper like Ahaz produced such a remarkably devout son.
My guess (and this is just a guess) is that Ahaz simply was not involved in raising his son at all. Even though Hezekiah was his heir, I would infer from v. 1 that Hezekiah was actually raised by his mother and not his father. Like many of the other good kings, v. 1 specifically names Hezekiah's mother, and I believe this detail was included because his mother was his primary caregiver in childhood. Furthermore, we know from many places in the bible that kings of Judah would commonly have multiple wives and children. It was common for them to have more than 10 children, and sometimes more than 40 or 50. At that kind of scale, it would be impossible for a single father to be involved in raising all of them even if he wanted to be (and it's not at all clear that they did). It's more likely that the burden of childcare was spread out over the mothers and possibly other servants or aides. From this perspective, the character of the child depends more on the nature of the mother than the father, which may help explain why so many good Israelite kings have bad children and vice versa.
Looking at the culture more broadly, there is a secondary question which is how did Judah flip-flop between following the LORD and following Baal from one generation to the next? If the country were so deeply involved with Baal worship during the reign of Ahaz, wouldn't they have resisted Hezekiah now when he is trying to reinstitute the temple system? More to the point, where did this faithful, God-fearing woman Abijah come from that Ahaz would marry her and that she would raise a faithful, God-fearing son in Hezekiah?
My perspective is that in Judah, we see a nation divided between two forces. Back in 1 Kings 18:21, Elijah similarly criticized Israel for having divided loyalties when he said, "How long will you hesitate between two opinions? If the LORD is God, follow him, but if Baal, follow him." My personal opinion is that in Judah, there was likely a group of people that diligently followed God even during the lifetime of Ahaz, and there was a group of people that diligently worshiped Baal even during the lifetime of Hezekiah. The king simply chooses which religion would take on preeminence in Judean society by encouraging one and suppressing the other. The king could control which religion was more visible, but could not root out or convert all the worshipers of the other religion.
Therefore I believe that Hezekiah's mother Abijah was one of many women who were faithful to the LORD during the reign of Ahaz, and they simply existing in the fringes of society while Ahaz moved Baal worship into the public places. When Ahaz died and Hezekiah came into power, all of these people came out of the shadows and went to the temple's opening ceremony.
On a personal note, I remember the first time I read through Kings and Chronicles that I was so deeply disappointed by the religious backsliding that occurs after Hezekiah dies (and similarly after Josiah's revival). When reading through the chapter, it feels like such a momentous occasion that I thought for sure the people would stay true to God. I would often wonder how the people could be so zealous for God and then suddenly it's like everyone changes for the worse when the good king dies.
I think my mental model for Judah's society was wrong. I imagined their society as if it were a single person who was changing his mind back and forth between these two gods. Instead, I think it's more accurate to picture it as a described above, with two communities that are existing side by side. One community may take the forefront, or the other community, but they are both still existing in tandem during the lifetimes of all of these kings. The life of Hezekiah is a great revival in a certain sense, but I think even during these great events there is a sizeable chunk of the population who are faithful to Baal and simply waiting for Hezekiah to die and one of "their own" men to become king. I think this makes it a lot easier to understand how the people of Judah could waver between these two gods with such intensity and so rapidly.
We can view Judah's gradual decline not as the emergence of some bad king drawing the whole nation away from God, but as a population shift over the years with more and more people following Baal and fewer and fewer following the LORD. It only took the bad kings to bring this moral erosion to light.
In the next chapter, Hezekiah continues his religious renewal by organizing the first Passover service in generations.