And it shall be answered, Because they forsook the Lord God of their fathers, which brought them forth out of the land of Egypt, and laid hold on other gods, and worshipped them, and served them: therefore hath he brought all this evil upon them. (2 Chronicles 7:22)
It was base ingratitude and treachery for Israel to turn away from the Lord, who had wrought such a marvelous deliverance for them in Egypt and who had established them in the Promised Land. Israel foolishly turned from a God who was everything and could do everything for His people to gods who were nothing and could do nothing (see on 1 Kings 9:9).