Facebook just reminded me of a post I made two years ago. It is a quote from Scott Hahn's "The Lamb's Supper." Two weeks ago my sermon focused on the cross, and I made reference to the sign of the cross. I thought that it would be good to post the Hahn quote here:
Among the early Christians, the sign of the Cross was probably the most universal expression of faith. It appears often in the documents of the period. In most places, the custom was simply to trace the cross upon the forehead. Some writers (such as St. Jerome and St. Augustine) describe Christians tracing the cross on the forehead, then the lips, and then the heart, as . . . just before the reading of the Gospel. Great saints also testify to the tremendous power of the sign.... St. Cyprian of Carthage, in the third century, wrote that "in the. . . Sign of the Cross is all virtue and power. . . . In this Sign of the Cross is salvation for all who are marked on their foreheads" (a reference . . . to Revelation 7:3 and 14:1). . . . St. Athanasius declared that "by the Sign of the Cross all magic is stopped, and all witchcraft brought to nothing." Satan is powerless before the cross of Jesus Christ.
(Scott Hahn, "The Lamb's Supper")