Evangelicalism has always been an eclectic movement, with believers picking and choosing what helps to advance the gospel, with the lodestar of Scripture as the ultimate authority for doctrine and practice. In recent years, some Evangelicals have begun to look to other traditions, not simply to inform their worship, but as alternate sources of authority. The high-profile conversion of some Evangelicals to Catholicism or Orthodoxy demonstrates this phenomenon; an embracing of the sacramental principle. Many converts accept Roman Catholic and Eastern Orthodox claims of continuity with the earliest church, without a more thorough investigation into the history of how the church developed. A closer look into the evidence tells a very different story. This book argues for a careful analysis of exactly what Evangelicals give up when they allow other sources of authority alongside Scripture, and for a re-engagement with the Bible as the sole ground of authority for the Christian life.