This paper argues that a more radical reconfiguration of public theology emerges through a pneumatological epistemology grounded in the event of Pentecost. As theologians such as Jürgen Moltmann, Amos Yong, and Willie James Jennings have suggested in different ways, the Pentecost event destabilizes established hierarchies of speech, redistributes theological agency beyond institutional elites, and generates a polyphonic community in which divine revelation becomes mediated through plural voices and unexpected locations. Pentecost therefore embodies a theological logic of marginality: knowledge of God emerges not from proximity to structures of power but from Spirit-enabled communities that exist in tension with hegemonic political and cultural orders. The argument will unfold in three movements. First, the paper examines the implicit epistemological assumptions within dominant models of public theology, particularly their reliance on institutional legitimacy and claims of neutrality within the public sphere. Second, it articulates a pneumatological epistemology shaped by Pentecostal decentering, highlighting how the Spirit destabilizes fixed structures of authority and reconfigures theological knowledge as participatory, relational, and distributed across the ecclesial body. Third, it explores the implications of this framework for ecclesiology and public theology, suggesting that the church's engagement with the public square should be understood not primarily through institutional representation but through Spirit-formed practices of constructive prophetic dissent (i.e. marginal witness) capable of exposing sacralized power and confronting structural inequality. In doing so, the paper contributes to ongoing debates on religion and inequality and proposes Pentecost as a theological paradigm for a decentered and critically engaged public theology.