Deuteronomy 29:24-26

24Then all the nations will ask, “Why has the Lord done all this to this land? What is this fierce, heated display of anger all about?”

25Then people will say, “Because they abandoned the covenant of the Lord, the God of their ancestors, which he made with them when he brought them out of the land of Egypt.

26They went and served other gods and worshiped them, gods they did not know and that he did not permit them to worship.