“He will devote...He will give.” The Hebrew text uses the prophetic idiom, putting the verb in the past tense to magnify the certainty of what God will do. So literally the text says that God has destroyed...He has given, but the event is in the future. [For more on the prophetic perfect, see commentary on Eph. 2:6]. To “devote to destruction” is to totally destroy. [For more on things “devoted” to Yahweh and devoted to destruction, see commentary on Josh. 6:17].
There is coming in the future a time of great tribulation upon the earth in which most of the people of earth will be killed (see commentary on Isa. 13:9).