Sign of the Cross

Question from Katie on 2/6/2008:  
I have been wondering why we should do the Sign of the Cross before and after praying. What does it mean? Is it wrong if i pray without doing the sign?
Answer by Matthew Bunson on 2/15/2008: 
The sign is used chiefly to make a profession of faith in the Holy Trinity and intercedes for a blessing upon the person making the sign as well as others and things.

The most distant origins of the Sign of the Cross are difficult to trace. However, the earliest testament to the practice was made by Tertullian around 230. He noted that tracing the sign of the cross on the forehead was a gesture of personal piety. The sign of the cross dates back to the early Church. Tertullian (c. 230) attests to the custom of tracing the sign on the forhead as a means of sanctifying the actions of daily life and as a gesture of piety. Further, the earliest initiation rites of the Church included tracing the sign of the cross on the forehead of a catechumen and at the initiation.

Giving the sign of the Cross is thus an act steeped in the oldest traditions of the Church.