On the first day of his second term, President Donald Trump signed Executive Order 14168 "Defending Women from Gender Ideology Extremism and Restoring Biological Truth," directing federal agencies to recognize only two genders, followed by additional orders on reproductive rights and LGBTQ issues including reinstating the Mexico City Policy and enforcing the Hyde Amendment. These actions reflect a pattern since the Obama administration of wildly swinging government support for family planning and cultural issues between administrations—not merely due to individual presidents' ideologies, but rather implementing longstanding party goals. This polarization represents a dramatic shift from an earlier era when both parties contained cultural conservatives and liberals, and party positions on these issues were far less predictable. This paper examines how the personal religious identities of elected officials drove durable shifts in the American party system since the 1960s, particularly regarding reproductive rights, LGBTQ rights, and civil rights. Building on extensive quantitative analysis of U.S. Senate behavior complemented by qualitative research, we show that partisan brands on cultural issues crystallized through the sorting of religious identities—with evangelical Protestants and Catholics acting as political entrepreneurs who remade their parties in their image—followed by gender sorting in the 1990s. We find that religion and gender independently predict roll-call voting on cultural issues, though partisan influence grows stronger over time as demographic sorting solidifies, ultimately creating a pro-life Republican Party and pro-choice Democratic Party through the deliberate branding efforts of specific senators who forced these issues onto the political agenda.