We enter on the history of the apostasy, and the root evil was that the bride of Jehovah had been unfaithful to her Lord. She looked on her glory as her own, and did not recognize that everything in it was the gift of God (Hosea 2:8).
The words obviously point to the policy which Solomon had initiated, of alliances with the heathen and the consequent adoption of their worship. This, as from the earliest days of Israel, was the "whoredom" (Revised Version) of the unfaithful with (Exodus 34:15, Exodus 34:16; Le Exodus 17:7; Deuteronomy 31:16; 2:17; Isaiah 1:21; Jeremiah 2:20; Hosea 1:1-11, Hosea 2:1-23).
And it was, so to speak, a promiscuous whoredom. Every passer by was admitted to her embraces, every nation that offered its alliance had its worship recognized and adopted. In the closing words of extremest scorn, the prophet adds, his it was.
Jerusalem was, as I have said, the Messalina of the nations.