The future of Christianity in America can be found by looking at one of this country’s longstanding religious traditions. The tradition I have in mind is not the white-steepled churches of New England Puritanism, or the Second Great Awakening’s populist Evangelical revivals. In fact, it is not even Christian. To understand the future, one must look instead at the Sun Dance of the Plain Indians. This three-hundred year-old ceremony, considered in the first section of this paper, recapitulates the whole world and relates Indians to all of life. This reintegrative function is what makes for successful modern American Christianity.Admittedly, such a ceremony seems an unlikely model for American Christianity in the twenty-first century, in a society where the division of labor and fragmentation of society observed by Max Weber has taken full effect. The modern world is structured in such a way that “major cultural and institutional spheres of society… develop [their] own institutional autonomy.” In other words, the various functions of life and institutions organizing them are separate: business and family, politics and religion are no longer assumed to have anything to do with each other. It is also home to a high degree of cultural pluralism, wherein urbanization, mass media, and social freedom allow for the coexistence of a wide array of individuals, groups, and communities.How, then, is the Sun Dance—an attempt at representing and reorienting all things, a task that seems to contradict the extraordinarily complex realities of modernity—a model for successful modern Christianity? People have a deep need for reintegration in the face of dizzying complexity and diversity. They want to know how to organize the world, and how to relate to it. Evangelicalism and Catholicism, two successful Christian groups in modern America, serve this function effectively. The second part of this paper will consider how by analyzing Evangelicalism’s orienting ideas and the Catholic Magisterium.Both Peter Berger and Robert Bellah have commented extensively on modern American religion. The final part of this paper will weigh their approaches in light of its main thesis of reintegration as the key to successful modern American Christianity. Berger’s prediction of religion’s future in “sheltering communities” is more accurate than Bellah’s claim that religious communities with the weakest ties to doctrinal orthodoxy and moral purity will thrive. But a successful modern Christian community does not merely shelter its members. It enables them to put the world together, just as the Sun Dance does.