In this chapter of Deuteronomy, the Lord said to the Israelites, "This very day, I will begin to put the terror and fear of you on all the nations under heaven. They will hear reports of you and will tremble and be in anguish because of you." (vs 25) This immediately made me think of the Israelites themselves when they were camped around the base of Mount Sinai. There was thunder and lightning and smoke, and the Israelites were trembling and afraid.
What was the purpose of that? To get their attention, so they would listen to what God had to say. Once they were listening, He wouldn’t have to resort to "raising His voice" to make Himself heard. And now, it seems He was planning to make Israel into a Mount Sinai for the surrounding nations. As reports got back to these heathen people, they were supposed to begin to tremble and be afraid — of Israel and their God. What was the purpose of that? To get their attention, so they would listen to what God had to say. Once they were "terrified" of Israel, they would be in a position to listen and hear that the God of Israel was good.
And how was this terror supposed to come about? It’s an interesting question, for all through this chapter, God is specifically forbidding the Israelites to war with the neighboring peoples. More than once, He said, "Do not harass them or provoke them to war, for I will not give you any of their land, not even enough to put your foot on." Hmmm, this doesn’t sound like the war-mongering, genocide-loving Old Testament God I’ve heard about.
In fact, the only war in the chapter occurs when Sihon king of Heshbon brought his army out and attacked Israel. Once they were attacked, they fought back, and they won a decisive victory. That probably got the attention of many of those surrounding nations. It’s no coincidence that God was bringing His people into a place where a myriad of heathen cultures lived and mingled. He loved all of those people just as much as He loved the Israelites, and He was anxious to get their attention, too!