have made a covenant with death … fashioned an agreement with Sheol: There are two possible interpretations:
The people had pledged themselves to the Canaanite god of death, Mot, for his supposed protection.
The prophet was sarcastic. The people believed their political and economic actions ensured their safety, but they had actually harmed themselves.
lies … and falsehood: The leaders did not see themselves as deceptive, but they were.