Now comes a gesture that is very familiar to Catholics but to the unitiated may also seem odd, (a kind of shoeing away of flies or something) and words are said that are grammatically incorrect! I’ll explain that later.
Standing at the Chair the celebrant begins the Mass with the sign of the cross. This gesture is perhaps one of the most recognizably Catholic traditions in any ecumenical gathering. You can always tell the Catholics immediately by this instinctive gesture deeply ingrained in any Catholic.
The origin of this gesture goes back to the earliest days of Christianity where it seems to have been more of sign of the cross traced on one’s forehead. Tertullian is said to have remarked in the early 3rd Century, “We Christians wear out our forehead with the sign of the cross!” This practice probably developed from Scriptural allusions to the Tau or “T” marked on the forehead of those to be saved from destruction (Ex. 17:9-14; Ez 9:4, Revelation 7:3, 9:4, 14:1). Over the years of the first centuries the practice seems to have developed of adding fingers to this tracing action. Two fingers representing the two natures of Christ were added as an act of faith against the monophysite heresy. Further developments took place to enhance the gesture. Now, by the fourth century three fingers (thumb, index and middle finger) are used to represent the Trinity and the other two fingers are folded back to the palm to represent the two natures of Christ. With all these symbolisms going on with the blessing hand it next developed that a larger area than the forehead was crossed. Now the downward motion tended to extend to the breast and eventually the whole chest was signed by reaching out to the shoulders. By the 9th Century the way to make the sign of the cross was pretty well spelled out by legislation from Rome and the Popes. As you can see the sign of the Cross became more than a way to bless oneself, it also became a statement of faith in the Trinity and in the two natures of Christ.
In the western Church as the monophysite controversy died down the Trinitarian faith has tended to take precedence and came to be spelled out with these words: “In the Name of the Father and of the Son, and of the Holy Spirit” to which all respond, “Amen.” Now have you noticed that this is not gramatically correct? Grammatically one should say, “In the names of the Father….Son and Holy Spirit.” But here too, going back to Scripture itself, the grammatical “error” bespeaks the truth that there is only ONE God, therefore one name, but there are three Persons in the One God.” So aren’t we clever here!
So the sign of the cross is an act of and a sign of Faith in the Triune God. It thus gives significance to all that is to follow in the Mass, placing it within the context of Faith. The Sign of the Cross is also a recollection of the Crucifixion. In this regard the Mass, as a making present of the once-for-all sacrifice of the Lord Jesus on Calvary, is especially suited to being opened by the sign of the cross. Lastly, and by extension, it is a visible movement into the Holy by all present since it puts demons to flight. Many of the Fathers of the Church speak of this aspect of the Sign of the Cross. For example, St. Cyril states that at the sign of the cross “demons tremble and angels recognize it. Thus the former are put to flight, while the latter gather about it as something pertaining to themselves.” (From his Catechetical Lectures). Historically the number of the signs of the cross throughout the Mass increased especially during the gothic period of the middle ages. The Old Latin Mass has a large number of signs of the cross. In the New Mass there has been the reduction of this number to two, one at the beginning the other at the end.
Now the last thing we should say about all this is that to make the sign of the cross is a bold gesture! In effect we are glorying in the Cross of Christ. We are not ashamed of it. Is this true for you? Many today are actually embarrassed by the cross. How is this you say? Well notice how they protest any time the Church articulates the demands of the Gospel. For example that we should turn away from sin, that babies should be brought to birth and never aborted, that Euthanasia is wrong and that we cannot simply do whatever we please and call it good. Many immediately protest and speak of the need for greater compassion and less strict norms etc. And many Catholics, far from defending the demands of the Gospel refuse to hold up the cross for others to see. Instead, embarrassed by the demands of the cross they refuse to affirm its power and its demands. Be careful before you make that sign of the cross! It means something. It means that we cannot simply refuse the demands of being a disciple but rather glory in the Cross of our Lord Jesus Christ.
Eastern Rite Catholics make the sign of the cross a little differently than Roman Catholics as depicted in this video: