Against contemporary trends that conceive of Christian worship primarily as entertainment or sheer celebration, Walter Sundberg argues that repentance is the heart of authentic worship. In Worship as Repentance Sundberg outlines the history of repentance and confession within liturgical practice from the early church to mid-twentieth-century Protestantism, advocating movement away from the "eucharistic piety" common in mainline worship today and toward the "penitential piety" of older traditions of Protestant worship.