Within historic Christianity, a martyr is one who dies for or is executed because of their Christian faith. Christian martyrs in the first three centuries A.D. were crucified in the same manner as Roman political prisoners or eaten by lions as a circus spectacle. They are recognized as martyrs because they preferred dying for their faith to apostasy (renunciation of faith). The Christian writer Tertullian (200 AD) asserted that "the blood of martyrs is the seed of the Church". Many church historians believe that there were more Christian martyrs in the 20th century than in the first 19 centuries combined. This claim is, however, difficult to confirm for obvious reasons.