2 Chronicles 19
And Jehoshaphat the king of Judah returned to his house in peace to Jerusalem.
2 And Jehu the son of Hanani the seer went out to meet him, and said to king Jehoshaphat, Shouldest thou help the ungodly, and love them that hate the Lord? therefore is wrath upon thee from before the Lord.
3 Nevertheless there are good things found in thee, in that thou hast taken away the groves out of the land, and hast prepared thine heart to seek God.
4 And Jehoshaphat dwelt at Jerusalem: and he went out again through the people from Beersheba to mount Ephraim, and brought them back unto the Lord God of their fathers.
5 And he set judges in the land throughout all the fenced cities of Judah, city by city,
6 And said to the judges, Take heed what ye do: for ye judge not for man, but for the Lord, who is with you in the judgment.
7 Wherefore now let the fear of the Lord be upon you; take heed and do it: for there is no iniquity with the Lord our God, nor respect of persons, nor taking of gifts.
8 Moreover in Jerusalem did Jehoshaphat set of the Levites, and of the priests, and of the chief of the fathers of Israel, for the judgment of the Lord, and for controversies, when they returned to Jerusalem.
9 And he charged them, saying, Thus shall ye do in the fear of the Lord, faithfully, and with a perfect heart.
10 And what cause soever shall come to you of your brethren that dwell in your cities, between blood and blood, between law and commandment, statutes and judgments, ye shall even warn them that they trespass not against the Lord, and so wrath come upon you, and upon your brethren: this do, and ye shall not trespass.
11 And, behold, Amariah the chief priest is over you in all matters of the Lord; and Zebadiah the son of Ishmael, the ruler of the house of Judah, for all the king's matters: also the Levites shall be officers before you. Deal courageously, and the Lord shall be with the good.
Jehoshaphat was a good king and spiritual leader, courageously calling his people to spiritual reformation and obedience to God. For this the Lord blessed him with “riches and honor” (2 Chron. 18:1). However, at the height of his prosperity, Jehoshaphat allowed his son Jehoram to marry Ahab’s daughter, Athaliah. In this way Jehoshaphat and his wife became in-laws with Ahab and Jezebel—the legendarily wicked first couple of Israel. As a consequence God withdrew His providential blessings. God does not play favorites (v 7). We can expect the same treatment from a holy and consistent God if, as Jehoshaphat, we persist in walking in paths of our own making.
Through His prophet Jehu, God made clear how displeased He felt by Jehoshaphat’s befriending the ecumenically minded, secular and prosperous Ahab (v 2-3). Although Jehoshaphat kept working on spiritual revival and reformation for his people, the consequences of this transgression to God’s explicit command furthered apostasy in the kingdom of Judah. A “little accommodation” of God’s commandments undid Jehoshaphat’s years of reforms.
Marriage outside of the faith is never a good idea. Neither is any accommodation of God’s will to the spirit and teachings of the world.