Joash was but just a boy when he became king over Judah, and while the priest that raised him was living Joash was loyal to both his mentor and to the Lord. The time came, however, that the priest died, and with that, coupled with counsel from those surrounding the king, “they abandoned the house of the Lord.” The Lord appealed to the king, but the king was going to have none of it; in fact, Zechariah, the son of Joash’s mentor, was killed as he spoke in the Lord’s name. From this point until his end, the Lord brought disaster upon the king and Judah.
Application: I think this illustrates well the depth of one’s teaching and foundation. It can appear that all things are as they should and could be, but as soon as a circumstance (or circumstances), or people of influence make their way into the recesses of a person’s heart, one just does not know how firm that foundation actually is.