God lists Israel's sins, from greed to injustice, to shedding innocent blood, to profaning the Sabbath, to every sexual sin in the Book. Prince, priest and prophet have all perverted their trusts. God will smelt them and remove the dross.
God continues describing Israel's idolatry as adultery, partly because the former involved the latter, often. God's people easily let their hearts follow the dominant culture of the day - Assyria then, Disney, Oprah and ESPN now. Judah did not learn from her sister Samaria's idolatry. Even seeing the result, she fell into the same sin.