In this chapter, Hezekiah hosts a magnificent Passover festival.
This is such a fascinating chapter to me. To the people who have only read this chapter and not the rest of the OT, it may not be clear why, so I will try to explain. First, I must set the context for this chapter.
Throughout the books of Exodus, Leviticus and Deuteronomy the LORD through Moses made it clear that the Israelites were absolutely expected to follow the letter of the Law. If a person accidentally sinned in some way, they could offer a sacrifice to make up for it (Lev 5:17), but the Law doesn't even have provisions for intentional sin. Except, perhaps, for purging the evil one from amongst you (Deut 17:7). It was just not supposed to happen.
Throughout the Law, and throughout the histories that followed, strict obedience to the Law was a hallmark of righteous figures (David's epic sin with Bathsheba notwithstanding). There is a certain logic to this. Placed in an environment where obedience to the Law is a central pillar of following God, it stands to reason that people who are sincere about seeking God will be meticulous in their obedience. All of the zeal and passion for God in this era is channeled towards getting all of these tiny details right, like offering sacrifices in just the right way, observing the Sabbath, ceremonial cleanliness, and so on. These things that seem so obscure and archaic to us would have been the bread-and-butter to an observant Judean, and just as importantly, failing to observe these things would clearly mark somebody as either apathetic about their faith or maybe even an idolater (both of which would be unthinkable to a righteous Israelite).
With all that in mind, the Judean people make so many mistakes in their Passover celebration. First, they celebrate the Passover in the wrong month (v. 2, c.f. Exodus 12:18) because the people simply weren't ready in time. In prior years, they had not celebrated the Passover at all (v. 5, 26) which is also a terrible sin. Lastly, the people failed to consecrate themselves before offering the Passover and ate the Passover while unclean (v. 17-18). These might seem like small things to you, but I think it's really important to understand how far outside of normal expected behavior this is. Even though it's clear from the passage that people had not been observing the Passover for a long time, the biblical text nevertheless maintains a very high standard for what people are supposed to do as followers of God. For example, there are many kings where it says "he did what was right in the eyes of the LORD, except the high places were not removed." (2 Kings 12:2-3 amongst others). To paraphrase, "the king got a bunch of things right, but not EVERYTHING. Not like David would have done." In many places David is held up as the standard of a righteous king, and nearly every other king falls short in one way or another. But for every king, the expectation is that the king would fulfill ALL of the requirements of the Law. That is the important part, the expectation of careful observance, which is emphasized every time the biblical text specifically calls out all of the things that one of the kings got wrong. If the authors of the bible did not care about these details, it would not have been mentioned.
Having all of this context, now it should be evident why this chapter is so striking. In spite of the expectation that the people would fulfill the details of the Law, and in spite of their failing to do so, God blesses the people in a direct and powerful way (with v. 27 concluding that "their voice was heard and their prayer came to his holy dwelling place, to heaven"). Verse 20 is another expression of God's grace, where he answers Hezekiah's prayer. Throughout the chapter, I think there is a strong sense that God's favor is resting upon this Passover and the Chronicler also views it favorably.
Several things in this chapter stand out. The first is that the people seem genuinely unprepared and possibly ignorant about the expectations of the Law. The second is that the people seem just as genuinely interested in seeking God by trying, as best as they can, to observe the Passover. The third is that Hezekiah and the other leaders acknowledge that they are not following the details of the Law (v. 2-3, 18-19). The fourth is that God appears to understand their situation, knows that they are coming from a great distance (both literal and figurative) to meet him, and he gives them overwhelming grace, forgiving their mistakes and answering their prayers and intentions.
God perceives the people based on their heart, their "heart to seek God", and God responds based on their heart and not based on their outward failures. Exodus 34:6 calls the LORD "compassionate and gracious", and we see it in many places throughout the OT but I personally don't think we see it anywhere more clearly than here. This chapter is like the opposite of the life of Saul. In 1 Samuel 13:9, Saul offered the burnt offering (which was a sin) because he wanted to make an external show of religiosity to encourage his men. God rejects Saul and later says, "man looks at the outward appearance, but the LORD looks at the heart." (1 Sam 16:7). In his outward appearance, Saul sinned, but God judged his heart as evil and corrupt and rejected him for it.
In this chapter, the people also have an outward sin, because they do not observe the Passover correctly. However, they have a "heart to seek God", and God sees it and he blesses them because of their heart. Saul had a selfish, greedy and malevolent heart, and God condemned him for it. What we learn from this chapter is that God does not reject the people whose hearts are genuinely and sincerely seeking him, no matter what kind of mistakes they make in their religious life or the way that they pursue him. If the heart is in the right place, God knows that they will eventually correct their outward behavior because he can send prophets to them and they will listen to his prophets and eventually their outward behavior can be fixed. If the heart is corrupt, then the outward behavior will never be right because they will not listen to his voice (through the prophets).
That is the most important theme of this chapter. There is one more point I would like to make before moving on, which is to highlight the cultural and religious division that appears in this chapter between the northern and southern kingdoms. It shouldn't be a surprise given the history of conflict we have been Israel and Judah, and because Jeroboam (the first king of Israel) established idols in Bethel and Dan specifically for preventing people from traveling to Jerusalem to worship the LORD. He did this because if the people continued traveling to Jerusalem to go to the temple, they might have been influenced by the priests or the king of Judah to orient their loyalties towards the southern kingdom, and this could have undermined the political stability of the northern kingdom.
None of this should be new to my readers, since earlier parts of Chronicles highlighted the conflict between north and south. What we see in this chapter is first, Hezekiah attempting a rapprochement of sorts with the north when he sends his messengers to call the people to the Passover (v. 5-6), and second, the majority of the northern people rejecting and mocking Hezekiah's invitation (v. 10). A small handful come to the Passover (v. 11), but the overwhelming majority of attendees are Judeans (v. 12), which is consistent both with Judah's traditional adherence to the LORD (for the most part) and also with Hezekiah's much greater influence over the people of his own kingdom versus the people of the northern kingdom.
In conclusion, the religious revival is a raging success, and in the next chapter Hezekiah continues by restructuring the tithe to support the Levites and priestly ministry.