When Ephraim spoke, there was trembling. He exalted himself in Israel, But when he became guilty in Baal, he died.
"But when he offended in Baal, he died ..." "The dying commenced with the introduction of the unlawful worship."[3]  It was appropriate that Ephraim should have been named here as a synonym for the whole northern Israel, because it was the Ephraimite king Jereboam I who led the way in corrupting the worship of God (1 Kings 12:30), "Ephraim's death warrant was sealed when he introduced idolatry."[4]  Other Old Testament passages relating to that corruption are  1 Kings 12:25ff and 16:29-33.  When God's covenant people forgot him and wallowed in the sensual immoralities of the old Canaanite paganism, their spiritual death ensued immediately; and the ultimate destruction of the kingdom became inevitable.