The Reformation of King Asa (Theonomy Applied)

King Asa, son of Abijah, was one of the great reformers of Judah. Scripture says this of him: 

And Asa did that which was right in the eyes of the Lord, as did David his father. (1 Kings 15:11)

Matthew Henry writes this about Asa:

He reigned forty-one years in Jerusalem, v. 10. In the account we have of the kings of Judah we find the number of the good kings and the bad ones nearly equal; but then we may observe, to our comfort, that the reign of the good kings was generally long, but that of the bad kings short, the consideration of which will make the state of God’s church not altogether so bad within that period as it appears at first sight. Length of days is in Wisdom’s right hand. Honour thy father, much more thy heavenly Father, that thy days may be long. II. The general good character of it (v. 11): Asa did that which was right in the eyes of the Lord, and that is right indeed which is so in God’s eyes; those are approved whom he commends. He did as did David his father, kept close to God, and to his instituted worship, was hearty and zealous for that, which gave him this honourable character, that he was like David, though he was not a prophet, or psalmist, as David was. If we come up to the graces of those that have gone before us it will be our praise with God, though we come short of their gifts. Asa was like David, though he was neither such a conqueror nor such an author; for his heart was perfect with the Lord all his days (v. 14), that is, he was both cordial and constant in his religion. What he did for God he was sincere in, steady and uniform, and did it from a good principle, with a single eye to the glory of God. (Matthew Henry's Commentaries, 1 Kings 15)

Here are important events in his reformation:

Suppresses Idolatry

And he took away the sodomites out of the land, and removed all the idols that his fathers had made. And also Maachah his mother, even her he removed from being queen, because she had made an idol in a grove; and Asa destroyed her idol, and burnt it by the brook Kidron. But the high places were not removed: nevertheless Asa's heart was perfect with the Lord all his days. (1 Kings 15:12-14)

And Asa did that which was good and right in the eyes of the Lord his God: For he took away the altars of the strange gods, and the high places, and brake down the images, and cut down the groves: And commanded Judah to seek the Lord God of their fathers, and to do the law and the commandment. Also he took away out of all the cities of Judah the high places and the images: and the kingdom was quiet before him. (2 Chronicles 14:2-5)

And the Spirit of God came upon Azariah the son of Oded: And he went out to meet Asa, and said unto him, Hear ye me, Asa, and all Judah and Benjamin; The Lord is with you, while ye be with him; and if ye seek him, he will be found of you; but if ye forsake him, he will forsake you. Now for a long season Israel hath been without the true God, and without a teaching priest, and without law. But when they in their trouble did turn unto the Lord God of Israel, and sought him, he was found of them. And in those times there was no peace to him that went out, nor to him that came in, but great vexations were upon all the inhabitants of the countries. And nation was destroyed of nation, and city of city: for God did vex them with all adversity. Be ye strong therefore, and let not your hands be weak: for your work shall be rewarded. And when Asa heard these words, and the prophecy of Oded the prophet, he took courage, and put away the abominable idols out of all the land of Judah and Benjamin, and out of the cities which he had taken from mount Ephraim, and renewed the altar of the Lord, that was before the porch of the Lord. (2 Chronicles 15:1-8)

And also concerning Maachah the mother of Asa the king, he removed her from being queen, because she had made an idol in a grove: and Asa cut down her idol, and stamped it, and burnt it at the brook Kidron. But the high places were not taken away out of Israel: nevertheless the heart of Asa was perfect all his days. And he brought into the house of God the things that his father had dedicated, and that he himself had dedicated, silver, and gold, and vessels. And there was no more war unto the five and thirtieth year of the reign of Asa. (2 Chronicles 15:16-19)

Covenants to Seek God

And he gathered all Judah and Benjamin, and the strangers with them out of Ephraim and Manasseh, and out of Simeon: for they fell to him out of Israel in abundance, when they saw that the Lord his God was with him. So they gathered themselves together at Jerusalem in the third month, in the fifteenth year of the reign of Asa. And they offered unto the Lord the same time, of the spoil which they had brought, seven hundred oxen and seven thousand sheep. And they entered into a covenant to seek the Lord God of their fathers with all their heart and with all their soul; That whosoever would not seek the Lord God of Israel should be put to death, whether small or great, whether man or woman. And they sware unto the Lord with a loud voice, and with shouting, and with trumpets, and with cornets. And all Judah rejoiced at the oath: for they had sworn with all their heart, and sought him with their whole desire; and he was found of them: and the Lord gave them rest round about. (2 Chronicles 15:9-15) 

Expels Sodomites 

And he took away the sodomites out of the land ... (1 Kings 15:12a)

Builds Fortifications for Defense of the Land

And he built fenced cities in Judah: for the land had rest, and he had no war in those years; because the Lord had given him rest. Therefore he said unto Judah, Let us build these cities, and make about them walls, and towers, gates, and bars, while the land is yet before us; because we have sought the Lord our God, we have sought him, and he hath given us rest on every side. So they built and prospered. And Asa had an army of men that bare targets and spears, out of Judah three hundred thousand; and out of Benjamin, that bare shields and drew bows, two hundred and fourscore thousand: all these were mighty men of valour. (2 Chronicles 14:6-8)

Trusts in God for Victory in Battle 

And there came out against them Zerah the Ethiopian with an host of a thousand thousand, and three hundred chariots; and came unto Mareshah. Then Asa went out against him, and they set the battle in array in the valley of Zephathah at Mareshah. And Asa cried unto the Lord his God, and said, Lord, it is nothing with thee to help, whether with many, or with them that have no power: help us, O Lord our God; for we rest on thee, and in thy name we go against this multitude. O Lord, thou art our God; let no man prevail against thee. So the Lord smote the Ethiopians before Asa, and before Judah; and the Ethiopians fled. And Asa and the people that were with him pursued them unto Gerar: and the Ethiopians were overthrown, that they could not recover themselves; for they were destroyed before the Lord, and before his host; and they carried away very much spoil. And they smote all the cities round about Gerar; for the fear of the Lord came upon them: and they spoiled all the cities; for there was exceeding much spoil in them. They smote also the tents of cattle, and carried away sheep and camels in abundance, and returned to Jerusalem. (2 Chronicles 14:9-15)