The Catholic Church in the United States occupies a paradoxical position as both a sacrament of God's reign and an obstacle to the social transformation it seeks to inspire. This paper examines the Church's role in shaping social engagement, its theological foundations, historical influence, and contemporary struggles. Drawing on Catholic social teaching, ecclesiology, and critical social analysis, this study evaluates how the Church has served as a catalyst for social movements such as civil rights, immigration justice, and economic equity while simultaneously upholding systemic inequalities, clericalism, and political divisions. Catholic social teaching offers a moral framework for addressing social injustices. These teachings have inspired Catholics to engage in movements aligned with the Reign of God—a vision of justice, peace, and human flourishing. However, institutional structures that promote these ideals have also maintained barriers to progress through hierarchical governance, exclusivist theology, and resistance to reform. Historically, the Catholic Church has played a pivotal role in social justice advocacy. Catholic leaders supported the Civil Rights Movement, fought for immigrant rights, and championed economic justice through labor movements. Yet, contradictions persist. Clericalism, institutional secrecy, and scandals have undermined the Church's credibility. Political entanglements and internal divisions further obscure its commitment to the Gospel's liberative message. This paper argues for a renewed ecclesial praxis that reclaims the Church's identity as a sacrament of liberation. A shift from clerical dominance to participatory leadership and from institutional self-preservation to authentic solidarity is essential. By renewing its commitment to justice and prophetic witness, the Church can transcend its historical limitations and embody the transformative power of the Gospel, fostering a more just and inclusive society.