Deeper Commentary

2Ch 22:1 The inhabitants of Jerusalem made Ahaziah his youngest son king in his place; for the band of men who came with the Arabians to the camp had slain all the older ones. So Ahaziah the son of Jehoram king of Judah reigned-
It could be that this band of men had preserved Ahaziah and were seeking for him to be a puppet king for them. LXX "the Arabians of Mazin". The usual rubric "and X his son was king in his place” is not quite followed here. It seems the succession was somehow questionable. And the fact his mother immediately took the throne after his death hints again at this.

2Ch 22:2 Forty-two years old was Ahaziah when he began to reign; and he reigned one year in Jerusalem. His mother’s name was Athaliah the daughter of Omri-
In fact the granddaughter of Omri. "Athaliah", 'Yah has constrained', may mean that she was bitter that Yahweh had as it were limited her; the same groundless complaint as in 2 Cor. 6:12. Ahaziah was 22 years old when he began to reign (2 Kings 8:26), but 42 in 2 Chron. 22:2. LXX has 20. But in Biblical Hebrew, numbers were expressed by single letters, and mem, forty, is very similar in orthography to caph, twenty. And that difference is even more probable in ancient Hebrew or 'Samaritan'. So this appears to be a case of where there were indeed slight errors in copying the Divinely inspired text.

2Ch 22:3 He also walked in the ways of the house of Ahab; for his mother was his counsellor to do wickedly-
His father had done the same (2 Chron. 21:6). So much sin and spiritual failure is due to a refusal to individuate from parental influence and be an independent person before God. "Counsellor" suggests she specifically instructed him in the ways of idolatry; and it was by listening to the wrong counsel that Rehoboam went wrong when the kingdom of Judah first began (s.w. 2 Chron. 10:8,9).  

2Ch 22:4 He did that which was evil in the eyes of Yahweh, as did the house of Ahab; for they were his counsellors after the death of his father, to his destruction-
The word for "counsellor" is associated with rulership and kingship; a king's counsellors were effectively the kings (Is. 1:26; 9:6; Ezra 7:28; 8:25; Job 3:14), and often in the Bible, the counsel of men is contrasted with that of God. We feel this tension too; for the counsel of God is so often different and opposed to the counsel of the majority of those looked up to for secular advice and counsel. See on 2 Chron. 25:16.    

2Ch 22:5 He walked also after their counsel, and went with Jehoram the son of Ahab king of Israel to war against Hazael king of Syria at Ramoth Gilead; and the Syrians wounded Joram-
Ahaziah was clearly intended to have learned from the experience of Jehoshaphat, who also went to war with Syria at Ramoth Gilead and was nearly slain there. He was only saved by grace, and afterwards experienced God's wrath for going there (2 Chron. 16:2). Circumstances and similarities repeat within our lives, and between our lives and those of people in the Biblical histories, in order that we might learn. Jehoram is called "Joram" within this same verse, perhaps because the name of God was no longer part of his name in practice.

2Ch 22:6 He returned to be healed in Jezreel of the wounds which they had given him at Ramah, when he fought against Hazael king of Syria. Ahaziah the son of Jehoram king of Judah went down to see Jehoram the son of Ahab in Jezreel, because he was sick-
As noted on :5, Ahaziah failed to perceive the similarities with the situation of Jehoshaphat.

2Ch 22:7 Now the destruction of Ahaziah was of God, in that he went to Joram; for when he had come, he went out with Jehoram against Jehu the son of Nimshi, whom Yahweh had anointed to cut off the house of Ahab-
There are a number of other passages which mention how "it was of the Lord" that certain attitudes were adopted by men, resulting in the sequence of events which He desired (Dt. 2:39; Josh. 11:20; 1 Sam. 2:25; 1 Kings 12:15; 2 Chron. 10:15; 22:7; 25:20). It is tempting to read Jud. 14:4 in this context, meaning that God somehow made Samson desire that woman in order to bring about His purpose of freeing Israel from Philistine domination. God through His Spirit works to confirm men in the path they wish to go. And this is the huge significance of the work of the Holy Spirit in our lives today.

Ahaziah was Ahab's grandson because of the intermarriage between the rulers of Israel and Judah. So Jehu did have a commission to kill him. But it would seem that Ahaziah could have avoided this had he not shown unity with Joram by visiting him when he was sick. Such is the flexibility of God's purpose, with so many potentials built into it, ever respecting the possibility of human repentance.

2Ch 22:8 It happened, when Jehu was executing judgment on the house of Ahab, that he found the princes of Judah, and the sons of the brothers of Ahaziah, ministering to Ahaziah, and killed them-
These were the very men who gave Ahaziah the wrong counsel to go and fight at Ramoth Gilead, and to worship the idols of Israel. There is no guilt by association taught in the Bible, but there is the fairly obvious teaching that we must be separate from the ways of those who are under Divine judgment. We are to come out of Babylon lest we be consumed in the judgment for her sins, we are to be separate from those whose bad company will corrupt us (1 Cor. 15:33).

2Ch 22:9 He sought Ahaziah, and they caught him (now he was hiding in Samaria), and they brought him to Jehu, and killed him-
Putting the records together, it seems that Ahaziah fled in his chariot through the garden house road (2 Kings 9:27), avoiding Jehu's call to slay him in his chariot. He got to Samaria and hid somewhere, Jehu's men searched for him and found him (2 Chron. 22:9), brought him to Jehu who was then "by Ibleam" (2 Kings 9:27), who struck him so hard that he eventually died of it, but he managed to again escape in his chariot to Megiddo, where he died of the wounds inflicted by Jehu. 

They buried him, for they said, He is the descendant of Jehoshaphat, who sought Yahweh with all his heart. The house of Ahaziah had no power to hold the kingdom-
They perceived the truth of God's overall judgment of Jehoshaphat, that his heart was with Yahweh, but it was his wrong associations with Israel which led to all this judgment upon his descendants.

2Ch 22:10 Now when Athaliah the mother of Ahaziah saw that her son was dead, she arose and destroyed all the royal seed of the house of Judah-
So obsessed was she with personal power that she killed her own relatives, perhaps her own children, in order to establish herself as the only living heir to David's throne. The royal family had already been depleted because of the murders of 2 Kings 10:14; 2 Chron. 21:4,17. She saw the significance of the promises to David, but twisted them into mere religion. For she was an idolater, Jezebel's daughter. 

2Ch 22:11 But Jehoshabeath, the daughter of the king, took Joash the son of Ahaziah, and stole him away from among the king’s sons who were slain, and put him and his nurse in the bedroom. So Jehoshabeath, the daughter of king Jehoram, the wife of Jehoiada the priest (for she was the sister of Ahaziah), hid him from Athaliah, so that she didn’t kill him-
In a sense, God's entire purpose through the line and seed of David depended upon the quick thinking of a young woman, and was concentrated in this small baby. For "all the royal seed" had been slain (:10). Her name means 'sworn to Jehovah', and this likely represents her later character rather than her birth name. She came from a bad background, but was married to the high priest (although we note Jehoiada is not listed in the list of high priests in 1 Chron. 6). "The bedroom" is better "the chamber of the beds", perhaps a room in the temple (:12) used for the storage of old beds and furniture. Or maybe this was where he was temporarily hidden, before being moved to somewhere in the temple (:12). We marvel at how Jehoiada kept his own faith in Yahweh strong (2 Chron. 23:1), although surely he must have been somewhat of an underground believer at this time.   

2Ch 22:12 He was with them hidden in God’s house six years; and Athaliah reigned over the land-
The temple was likely relatively disused, as Athaliah was such a strong worshipper of Baal. Therefore Joash later had to majorly repair it. However in 2 Chron. 23:1-8 we do read of its usage, but perhaps not as it was before. It could be inferred from 2 Chron. 23:18 that the burnt offerings were not offered during Athaliah's dictatorship. And 2 Chron. 24:7 is clear: "For the sons of Athaliah, that wicked woman, had broken up God’s house". See on 2 Chron. 24:13 for the extent of the damage done. So they hid the child in one of the disused chambers for the priests of Yahweh, who likely were not regularly officiating any more at that time. We note how Jehoshabeath and her husband Jehoiada the priest (2 Chron. 22:11) would have had access to both the palace and the temple because of their positions. And although they must have been underground believers to some extent, they used their connections well, to keep alive the line of David. Joash became king at seven, so he was a one year old baby when saved from Athaliah.