Hosea prophesied in a dark and melancholy period of Israel's history, the period of the Northern Kingdom's decline and fall in the 8th century BCE. The sins of the people, their priests and their rulers had brought upon them great national disasters. Their various sins (homicide, fornication, perjury, theft, idolatry, impiety and others) are mentioned and criticized. An interpolated list of kings made Hosea into a contemporary of Isaiah.
The book may be divided into two parts, the first containing chapters 1-3, and symbolically representing the idolatry of Israel under imagery borrowed from the matrimonial relation; Hosea marries a prostitute, as the Lord said, "The people in this land have acted like prostitutes and abandoned the Lord."
The figures of marriage and adultery are common in the Old Testament writings to represent the spiritual relations between God and the people of Israel. Here we see the apostasy of Israel and their punishment, with their future repentance, forgiveness, and restoration.
The second part, containing 4-14, is a summary of Hosea's discourses, filled with denunciations, threatenings, exhortations, promises, and revelations of mercy.