In this popular work of apologetics, Mark Shea presents a lively and entertaining look at his conversion to Catholicism from Evangelicalism and his discovery of Christian Tradition. As an Evangelical, Shea accepted the principle of Sola Scriptura (Scripture alone) as the basis of faith. Now as a Catholic convert, he skillfully explains how and why Sacred Tradition occupies a central role in divine revelation.

Tracing his own journey of intellectual and spiritual awakening, Shea begins by looking for a rejoinder to those modern-day false prophets who would claim that Scripture itself is not to be trusted, and he ends with his conviction that Tradition, as explained by the Catholic Church, is the only sure guarantee of the truth of the revelation of Jesus Christ.  

Note: This is an abridged version of By What Authority? 



"A crystal clear and compelling case for Sacred Tradition, on the basis of logic, history, and Scripture. It is simply the best I have found." 
- Scott Hahn, Author of Rome Sweet Home

"This is not just another book of Catholic apologetics. It is not only a good thing; it's also a good read. Concrete, clear, compelling arguments."
- Peter Kreeft, Author of Handbook of Catholic Apologetics

"An important service for Catholics, Evangelicals, and all those seeking a firm grounding for faith. Shea argues powerfully for the extra-biblical authority of Sacred Tradition as a depository and source of revelation side by side with the Bible, to which it testifies and which it interprets with authority."
- Russel Shaw, Author of American Church 

Book Dimensions: 5.5" x 8.5"