Zephaniah introduces the theme of judgment at the outset probably because of the consensus perspective of the day. Such a perspective had been warped by exposure to, and promotion of, all sorts of perversion and idolatry.
This was a generation that had devoted itself to compromise (Zephaniah 1:4–5) and was unconcerned about following the Lord (Zephaniah 1:6). Zephaniah must first try to make the people realize how far they had strayed from what was right and how horrendous the consequences of their conduct would be.
1 And so he starts out with judgment because there was to be no more contention on the subject, for their iniquity had become quite ripe.
2
2 “I will utterly sweep away everything from the face of the earth,” declares the LORD.