Joash and Jehoiada

“Joash did what was right in the eyes of the Lord all the years of Jehoiada the priest.” 2 Chronicles 24:2
Joash was the only surviving son of Ahaziah after Azaliah the queen mother killed all the other heirs to the throne (2 Chr. 22:10). He was hidden in the temple for six years (2 Chr. 12:22) and was made king at age seven, the youngest of all the kings of Judah.
Joash had the perfect upbringing with regards to opportunities for spiritual education. He was raised by Jehoiada the priest, who became like a father to him – establishing him on the throne of Judah, finding wives for him, advising him. Jehoiada would certainly have trained Joash in the ways of the Lord.
Yet Joash only did what was right in the eyes of the Lord while Jehoiada was alive. He was the one who collected money from the people and ordered repairs to be carried out on the temple. But when Jehoiada died, Joash turned away from God and followed the ways of his officials, worshipping and serving the Canaanite gods (2 Chr. 24:17-18). When Jehoiada’s son Zechariah prophesied against Joash, he had him executed (2 Chr. 24:22).
I don’t know why Joash forsook God after Jehoiada died. I guess you never know who is truly saved until they have to stand for God for themselves.