In First Kings, chapter fifteen, verse three begins with Abijam, king of Judah. So his reign began with Jeroboam’s eighteenth year, continued his whole nineteenth year, and ended within his twentieth year, equal three years. The son of his mother, Maachah, the daughter of Abishalom: walked in all the sins of his father. The not perfect heart typically refers to one who is an idolator. The soul of David is said to be perfect because he never turned after other gods: to have a perfect heart does not imply moral perfection.
This adoption of the idolatries of Rehoboam did not prevent Abijam from representing himself as the champion of the temple and the priesthood against the rival worship of Jeroboam and dedicating treasures. Perhaps the spoils of his victory in the house of the Lord. From the qualified phrase “his heart was not perfect before God,” it may be inferred that, like Solomon and Rehoboam, he professed to worship Jehovah only as the supreme God of his temple. It is a curious irony that he should be as inveighing against the degradation of His worship in Israel while he countenanced or connived at the worse sin of the worship of rival gods in Judah.
Abijam was not perfect with the Lord his God and wanted sincerity: he began well but fell off and walked in all the sins of his father. Following his bad example, though he had seen the consequences of it, the family of David continued as a lamp in Jerusalem to maintain the true worship of God there. When the light of Divine truth became ruined in all other places, the Lord still took care of his cause, while those who ought to have been serviceable have lived and perished in their sins. The Son of David will continue to light his church, to establish it in truth and righteousness to the end of time. There are two kinds of fulfilling the law, one legal, the other by the gospel.