If you want to be my disciple, you must hate everyone else by comparison, — your father, mother, wife, children, brothers and sisters, — yes even your own life. Otherwise, you cannot be my disciple. – Luke 14:26

God had sent in reinforcements to assist King Josiah, the prophet Zephaniah.  We see in 2 Chronicles 34:3a, Josiah began to seek God when he was 16 years old.  At 20 years old he began purifying Judah and Jerusalem, destroying ALL the pagan shrines, the Asherah poles, and the carved idols and cast images. – 34 Chronicles 34:3b. And it wasn’t until he was 26 years old, that the Book of the Law was found.

The king took his place of authority beside the pillar and renewed the covenant in the Lord’s presence. He pledged to obey the Lord by keeping all his commands, laws, and decrees with all his heart and soul. He promised to obey all the terms of the covenant that were written in the scroll.  And he required everyone in Jerusalem and the people of Benjamin to make a similar pledge. The people of Jerusalem did so, renewing their covenant with God, the God of their ancestors. – 2 Chronicles 34:31-32

If everything seems to be flowing along just fine, why does God send Zephaniah to the people of Judah (http://www.biblehub.com/nlt/zephaniah/1.htm) slamming down his fist,  preaching fire and brimstone, and the imminent wrath of God?

It is because of what we read above in 2 Chronicles 34:31-32. Josiah sought God, Josiah repentant inwardly. And perhaps even more importantly those inward convictions resulted in outward/visible signs of repentance, and his trust and hope in God.  The people of Judah and Jerusalem, however, did not share King Josiah’s conviction.  Sure they obeyed the King’s orders, renewing their covenant with God. But they only did that because He (KING Josiah) required everyone to pledge the faith in God. – 2 Chronicles 34:32

The people of Judah and Jerusalem only paid the king, and God, lip-service. They honor me with their lips, but their hearts are far from me. – Isaiah 29:13