The Old Testament repeatedly mentions prostitution in relation to sin against the first commandment. The Lord God established a bond of love between himself and people (specifically Israel, Exodus 20:1–17) of which marriage was a reflection (Ephesians 5:22). Serving other gods (idolatry) amounted to spiritual adultery, so that Israel was termed a “whore” (prostitute) in places like Isaiah 1:21, Jeremiah 3:1, Ezekiel 16:15–22, and Hosea 1:2. The reason for serving other gods always revolved around the expectation that the idol could provide Israel’s needs better than the Lord could (Deuteronomy 8:11–20; Matthew 6:24). Inasmuch as cities and states have ability to provide daily wants, the Old Testament describes Israel as committing harlotry with Egypt, Assyria, and Babylon (Ezekiel 16:26–34). More, as cities and states could entice Israel to commit prostitution (seek her happiness in the stuff these cities or states could offer—wealth, security, freedom, credibility, etc.—instead of in her divine Spouse alone), the Old Testament depicts cities as prostitutes (Isaiah 23:15–18 regarding Tyre; Nahum 3:4 regarding Nineveh). Of course, Jerusalem also played the role of a prostitute (Isaiah 1:21; Jeremiah 2:20). So in John’s day the tag “prostitute” could be applied to so many cities and states that tempted people through their wares and their policies to find their happiness in earthly stuff (wealth, health, freedom, marriage, work, etc.). That remains equally true today. The addition of the adjective “great” could reasonably direct a reader’s thoughts to Rome as the capital city of the Roman Empire – and hence most attractive and influential and appealing in her enticements. Better, however, is to understand the adjective “great” as an expression of how effective the prostitute was in her enticements.