“their lies.” This likely refers to the idols that they follow, because they are the same things their “fathers” (ancestors) followed after, but it could then also refer to the words of the false prophets of those gods, e.g. the prophets of Baal, etc. The NIV has, “they have been led astray by false gods, the gods their ancestors followed,” and that gets the main sense of the text. God uses descriptors such as “Worthless,” and “Lies” to describe idols. Many people in Judah were following pagan gods, as we know from Kings and Chronicles and other prophets such as Jeremiah.