See 2 Kings 8:18. The writer of Kings only tells us in general terms that Jehoram "did evil in the sight of the Lord," and "walked in the way of the house of Ahab." Here, in 2 Chronicles 21:11, 2 Chronicles 21:13, we have particulars of his idolatry. Jehoram, it seems, seduced by the evil influence of his wife - Athaliah, the daughter of Ahab - permitted the introduction of Baal-worship, idolatrous altars in various high places, groves (Asherahs), images, and pillars; the people were not only allowed, but compelled to take part in the new rites. "To commit fornication" is a common metaphor, signifying idolatry or spiritual unfaithfulness (compare the 2 Kings 9:22 note).

To commit fornication - That is, to serve idols. The Israelites were considered as joined to Jehovah as a woman is joined to her husband: when she associates with other men, this is adultery; when they served other gods, this was called by the same name, it was adultery against Jehovah. This is frequently the only meaning of the terms adultery and fornication in the Scriptures.

Moreover, he made high places in the mountains of Judah,.... Temples and altars for idols, which, being built on mountains, had the name of high places; and these Jehoram made or rebuilt were those which had been pulled down by Asa and Jehoshaphat:

and caused the inhabitants of Jerusalem to commit fornication; that is, idolatry, drawing them by his own example to worship Baal, for he did what Ahab and his family did, 2 Chronicles 21:6, and compelled Judah thereto; the inhabitants of Jerusalem falling into the same idolatrous practice with him, he forced the inhabitants of the cities, and in the country, to do the same, who it seems were not so willing and ready to comply therewith.

Moreover he made high places in the mountains of Judah, and caused the inhabitants of Jerusalem to commit {f} fornication, and compelled Judah thereto.

(f) Meaning, idolatry because the idolater breaks promise with God as the adulteress does to her husband.

21:11 High places - Not to the Lord, but to Baals or false gods. And caused - Not only by his counsel and example, but by force, by threats, and penalties.

21:1-11 Jehoram hated his brethren, and slew them, for the same reason that Cain hated Abel, and slew him, because their piety condemned his impiety. In the mystery of Providence such men sometimes prosper for a time; but the Lord has righteous purposes in permitting such events, part of which may now be made out, and the rest will be seen hereafter.