Book excerpt: Twenty years ago, not one nation on earth had legal same-sex marriage. Now, access to same-sex marriage is increasingly seen as a basic human right. In a matter of less than a generation, western cultures have experienced a moral revolution. Dr. R. Albert Mohler examines how this transformation occurred, revealing the underlying cultural shifts behind this revolution: the acceptance of divorce culture, liberation of sex from reproduction, the prevalence of heterosexual cohabitation, the normalization of homosexuality, and the rise of the transgender movement. He then offers a deep look at how the Bible and Christian moral tradition provide a comprehensive understanding upon which Christians can build their personal lives, their marriages, church ministry, and cultural engagement. Dr. Mohler helps Christians in their understanding of the underlying issues of this significant cultural shift and how to face the challenge of believing faithfully, living faithfully, and engaging the culture faithfully in light of this massive change.