Thus the prototype of the Christian witness is the martyr. Indeed, the original Greek word simply meant "witness". Its usage was not confined to those who had died for the faith; rather, all who had suffered persecution "for the sake of the Name" (Acts 5:41) were witnesses, "martyrs". And their witness was not simply to their own convictions, powerful as they were, but to the demands of living in the truth as these witnesses had been grasped by that truth in the person of the Risen Christ.
--George Weigel, "The Sovereignty of Christ and the Public Church", in Against the Grain: Christianity and Democracy, War and Peace, 2008