The events of these chapters illustrate the disastrous results of Jehoshaphat's alliance with Ahab of the Northern Kingdom. This compromise led to the marriage of his son Jehoram with Athaliah, the daughter of Ahab and the infamous Jezebel. Jehoram did not walk in the ways of his father, but in the evil ways of his father-in-law, Ahab. His marriage to a pagan woman had a bad influence on him. Sadly, the great reformation of his father, Jehoshaphat, did not affect Jehoram. When he became king, he killed all of his brothers and some other leaders of the people (21:4). This was possibly so they could be no threat to him, politically or religiously (21:13); or it may have been from a greedy desire to take all the wealth of Jehoshaphat for himself (21:3).
Jehoram turned the people away from the Lord by encouraging idolatry and even the worship of Baal, the cultic religion of his wife. Her mother, Jezebel, had brought this to the Northern Kingdom from her home country of Phoenicia. As well as these pagan practices involving fornication, there was also spiritual adultery and harlotry against God, their divine husband (cf. Leviticus 20:5). The prophet Elijah prophetically wrote a letter of condemnation and doom to Jehoram, which interestingly may have been written by the inspiration of the Holy Spirit even before Jehoram took the throne. The letter accused him of spiritual harlotry and predicted that the Lord would strike his family and that he would suffer and die because of a severe intestinal sickness. Though Elijah was a mighty prophet of God, Jehoram ignored these words and continued in his evil ways. The prophecy did indeed come to fulfillment just as Elijah had spoken. Because Jehoram forsook the Lord, his life was tragic: the nation suffered defeat and their treasures were carried away (21:16-17). All his wives and children, with the exception of his wife Athaliah and his youngest son Jehoahaz (whose name means "the Lord has taken"), were also taken away. Jehoram's life ended with much pain and suffering due to his intestinal sickness. He was not even given an honourable burial (21:19; 16:14), and no one mourned his death. Jehoram certainly reaped what he had sown. His life is a tragic example of what .can happen when someone forsakes the Lord.
Although Ahaziah (also called Jehoahaz, 21:17) was evil, he was the only one left in the royal dynasty of David to take the throne; they had no other choice but to make him king. This youngest son of Jehoram and Athaliah reigned only one year over Judah, but during this time he also walked in the ways of his father and of his grandfather Ahab. Just as his mother had been a bad influence on his father, she also influenced him to do wicked things. The counsel he received from her, and other relatives from the house of Ahab, led him to destruction (22:3-4). In the plan of God, Ahaziah met his death while helping his uncle Jehoram (also called Joram) of Israel against Jehu, the man that God had chosen to bring judgment upon the house of Ahab (cf. 1 Kings 19:16-17; 2 Kings 9).
Athaliah saw her son's death as an opportunity to usurp the throne of Judah. She murdered any heir to the throne, who were her own grandchildren! She almost, but for the providence of God, exterminated the dynasty of David; this was yet another terrible result of Jehoshaphat's compromise by his treaty with Ahab. Athaliah strengthened the worship of Baal in Judah, just as her mother had done in Israel, but what else could be expected of the daughter of Jezebel who became a notorious symbol of the embodiment of evil? (cf. Revelation 2:20-21).
The plan of God, however, was to prevail over her evil schemes. A daughter of King Jehoram, a sister of Ahaziah named Jehoshabeath, rescued and hid her one-year-old nephew Joash from Athaliah. God saved one descendant of David to see His plan for the redemption of the world come through the Messiah Jesus, the Great Son of David. Evil forces cannot stop God's divine plans.