Gross Domestic Product (GDP) has dominated national development policy for decades, yet it largely neglects relational, spiritual, ecological, and ethical dimensions of collective well-being. As global crises—from climate change to social fragmentation—expose the limits of growth-driven paradigms, alternative frameworks emphasizing relationality, ecological ethics, and spiritual worldviews are increasingly urgent. This paper proposes a spiritual-postgrowth architecture integrating four epistemological traditions: Ubuntu philosophy, Christian theological ethics, Indigenous cosmologies, and the Andean paradigm of Buen Vivir. Drawing on contemporary scholarship, the paper critiques GDP, explores how spiritual and relational values redefine well-being, and outlines policy implications for governance, ecological stewardship, and leadership. The framework advances a postgrowth theory emphasizing relationality, stewardship, and ecological regeneration.