This announcement indicates the occasion of a theophany, an appearance of the Lord God. The Hebrew term for awesome
(נוֹרָא)is a passive form of the verb meaning to fear.
The Lord will be feared. His awesomeness is "that overwhelming quality associated with his incomparability in character and deed, often manifested in his wars of judgment (Exodus 15:11; Deuteronomy 7:21; Joel 2:11, Joel 2:31; Malachi 4:5).”1 His incomparability in character and deed can only inspire fear and awe.
Long before the time of Zephaniah, the Lord assured his people that he intended to make them possess the nations. He called them not to be in dread of such nations, “for the Lord your God is in your midst, a great and awesome God [וְנוֹרָא]. The Lord your God will clear away these nations before you little by little” (Deuteronomy 7:21–22). He called his people to fear him alone, for the Lord your God is God of gods and Lord of lords, the great, the mighty, and the awesome God [וְהַנּוֹרָא]
(Deuteronomy 10:17). Now in Zephaniah 2:9, the Lord reiterates his intention to bring Judah’s neighbours to submission by restating his awesome nature, which he will set against them.2
11 The LORD will be awesome against them; for he will famish all the gods of the earth, and to him shall bow down, each in its place, all the lands of the nations.