Albert Barnes Commentary 2 Chronicles 34:33

"And Josiah took away all the abominations out of all the countries that pertained to the children of Israel, and made all that were found in Israel to serve, even to serve Jehovah their God. All his days they departed not from following Jehovah, the God of their fathers." — 2 Chronicles 34:33 (ASV)

All his days they departed not - This must be understood in the letter rather than in the spirit. There was no open idolatry in the reign of Josiah, but the reformation was superficial rather than genuine, shallow rather than searching and complete (compare the marginal reference).