Zephaniah reveals that only the judgment of God can cleanse Judah of the sins that she has committed. The day of the Lord is coming and the nation must prepare for its salvation. According to the genealogy at the beginning of the book, Zephaniah was active during the reign of King Josiah.

Zephaniah 2

2:2 Before the decree bring forth, before the day pass as the chaff, before the fierce anger of the LORD come upon you, before the day of the LORD'S anger come upon you.