29Then the king called together all the elders of Judah and Jerusalem. 30He went up to the temple of theLord with the people of Judah, the inhabitants of Jerusalem, the priests and the Levites—all the people from the least to the greatest. He read in their hearing all the words of the Book of the Covenant, which had been found in the temple of the Lord. 31The king stood by his pillar and renewed the covenant in the presence of the Lord—to follow the Lord and keep his commands, statutes and decrees with all his heart and all his soul, and to obey the words of the covenant written in this book.
But the king and the people did not just read the Book, they renewed the covenant and then sealed it with the second restorative Passover (like Hezekiah's). The ironic thing is this renewal did not save them. It made them very aware that they were in danger of losing their land because they had forsaken their god. While the people renewed their faith under Josiah's lead, they fell right back into backsliding away from God after Josiah's untimely death.
From Josiah's grandfather, Manasseh's, time on the people became like a ping pong ball batted between Egypt in the south and the powers of Syria, Assyria, Babylon, Persia, and Greece in the north. Josiah's effort to battle against the king of Egypt was totally outmatched, and a terrible mistake by the godly king. Normally Judah fought only defensive wars- but this was an offensive one. Hezekiah was the last Judean king to win a victory until the Maccabees (a few years before Christ).