St. Augustine wrote a book in the 400s after the fall of Rome called The City of God. His point was that even if human cities are destroyed, there is a spiritual city made of people who believe in God that cannot be destroyed. The "two loves" are a love of self vs love of God. James Boice took that idea in the '90s to write about how even if American/Western culture is falling apart, Christians have a responsibility to live moral lives as good citizens.