Historical context. Judah and Israel are in a perpetual state of decline from the Glory days of David and Solomon who ruled over a united nation of Israel. Jehoiada was High Priest at the time of Jehoash the 8th King after David of the Southern Kingdom of Judah. Jehoiada may have been as old as 90 years at the time of Jehoash's kingship. He would have witnessed I believe the kingships of Jehosophat, Jehoram, Ahaziah and Jehoash.
That unity and glory of Israel and Judah has been decimated in large part due to the unfaithfulness of both Judah and Israel and especially their kings who led the nation into sin. This sin manifested itself especially in the idolatry that occurred as early as Solomon, the wealthiest and wisest king and last king over a united Israel and Judah. Strangely enough it is Solomon who would have built the temple of God , witnessed God's presence fill that Temple and heard God's speaking to him directly in a dream after the dedication of this temple.
1 Kings 9 When Solomon had finished building the temple of the Lord and the royal palace, and had achieved all he had desired to do, 2 the Lord appeared to him a second time, as he had appeared to him at Gibeon. 3 The Lord said to him: “I have heard the prayer and plea you have made before me; I have consecrated this temple, which you have built, by putting my Name there forever. My eyes and my heart will always be there. 4 “As for you, if you walk before me faithfully with integrity of heart and uprightness, as David your father did, and do all I command and observe my decrees and laws, 5 I will establish your royal throne over Israel forever, as I promised David your father when I said, ‘You shall never fail to have a successor on the throne of Israel.’ 6 “But if you[a] or your descendants turn away from me and do not observe the commands and decrees I have given you[b] and go off to serve other gods and worship them, 7 then I will cut off Israel from the land I have given them and will reject this temple I have consecrated for my Name. Israel will then become a byword and an object of ridicule among all peoples. 8 This temple will become a heap of rubble. All[c] who pass by will be appalled and will scoff and say, ‘Why has the Lord done such a thing to this land and to this temple?’ 9 People will answer, ‘Because they have forsaken the Lord their God, who brought their ancestors out of Egypt, and have embraced other gods, worshiping and serving them—that is why the Lord brought all this disaster on them.’”
Solomon initially followed the Lord and did many great things but then 1 Kings 11 King Solomon, however, loved many foreign women besides Pharaoh’s daughter—Moabites, Ammonites, Edomites, Sidonians and Hittites. 2 They were from nations about which the Lord had told the Israelites, “You must not intermarry with them, because they will surely turn your hearts after their gods.” Nevertheless, Solomon held fast to them in love. 3 He had seven hundred wives of royal birth and three hundred concubines, and his wives led him astray. 4 As Solomon grew old, his wives turned his heart after other gods, and his heart was not fully devoted to the Lord his God, as the heart of David his father had been. 5 He followed Ashtoreth the goddess of the Sidonians, and Molek the detestable god of the Ammonites. 6 So Solomon did evil in the eyes of the Lord; he did not follow the Lord completely, as David his father had done7 On a hill east of Jerusalem, Solomon built a high place for Chemosh the detestable god of Moab, and for Molek the detestable god of the Ammonites. 8 He did the same for all his foreign wives, who burned incense and offered sacrifices to their gods.9 The Lord became angry with Solomon because his heart had turned away from the Lord, the God of Israel, who had appeared to him twice. 10 Although he had forbidden Solomon to follow other gods, Solomon did not keep the Lord’s command. 11 So the Lord said to Solomon,“Since this is your attitude and you have