Rehoboam’s enemy could only strengthen him. It was Rehoboam himself who weakened Judah.
Things seem to be looking up for Rehoboam’s administration. The cities of Judah have been militarily fortified. But Judah couldn’t be truly strong unless, like us, they were spiritually fortified. In the north, it’s stated concerning the priests and Levites who had land holdings throughout the ten tribes that “Jeroboam and his sons had rejected them from serving as priests” (2 Chron 11:14). So abandoning their ancestral homes, they flooded south to the Holy City. This should have been a real boost for Rehoboam’s reign because “the priests and the Levites who were in all Israel took their stand with him” (v 13). But there was more. When Jeroboam formulated his new quasi-religion, he “appointed for himself priests for the high places, for the demons, and the calf idols which he had made” (v 15). Who were these “priests”? Not from the tribe of Levi, but “whoever wished, he consecrated him” (1 Ki 13:33). Do-it-yourself priests and make-them-yourself gods! No surprise, then, that “those from all the tribes of Israel, such as set their heart to seek the Lord God of Israel, came to Jerusalem to sacrifice to the Lord God of their fathers” (2 Chron 11:16). The result was that “they strengthened the kingdom of Judah” (v 17). Can you see the pendulum swing? Bad decision to ignore the wise elders, and he loses 10 tribes. Good decision to listen to God’s prophet, a civil war with Israel is averted, and instead he fortifies Judah. Then after three years of this godly influence, another bad decision, “when Rehoboam had established the kingdom and had strengthened himself, that he forsook the law of the Lord” (12:1). What is it about us frail and foolish humans? In struggles, we go to God for help. When He helps us, we take the credit. Lord, save us from ourselves!