Origins of the Sign of the Cross

The Christian custom of gesturing the sign of the cross was originally with the right hand's thumb only and across the forehead only. (St. John Chrys., Hom. ad pop. Antioch. xi; St. Jerome, Ep. ad Eustochium.) The custom originated during the second century.

Vestiges of this earliest gesture still exist when Catholics sign a cross on their forehead to hear the Gospels during mass, when their foreheads are marked with ash on Ash Wednesday, when applying the holy oil (called chrism) on the forehead for the sacrament of Confirmation, and so on. Around year 200 in Carthage (modern Tunisia, Africa), Tertullian says: "We Christians wear out our foreheads with the sign of the cross" (Latin: "Frontem crucis signaculo terimus") (De Cor. mil. 3). The second century Christians signed the cross on their forehead before taking any risk, such as embarking on a journey, and so on.

Tertullian points out that the sign of the cross is not commanded in any Holy Scripture. It is only from Christian cultural tradition. A search for a scriptual prooftext for the sign of the cross has required loose interpretations. For examples: "Go throughout the city of Jerusalem and put a mark [of ash?] on the foreheads of those who grieve and lament over all the detestable [idolatries] that are done in it" (Ezekiel 9:4). "Do not harm the land or the sea or the trees until we put a seal [with holy oil?] on the foreheads of the servants of our God." (Revelation 7:3). And so on. Of course, none of these biblical prooftexts prescribe a motion of a cross, but their location on the forehead probably informed the early Christian custom.

By the fourth century, the sign of the cross involved other parts of the body beyond the forehead. (St. Ambrose, De Isaac et animâ, Migne, P. L., XIV, 501-34.) By the sixth century, these variations of smaller signs across the body conflated into one larger sign from forehead to sternum, like the Orthodox Christians use now. At this time, the signing of the larger cross was also choreographed with three fingers (including the thumb) to represent the Trinity and with the phrase in Latin: "In nomine Patris, et Filii, et Spiritus Sancti".

Originally, when signing the large sign of the cross on oneself, the movement of the hand was from right-to-left. The Eastern Orthodox Church still preserves this motion today. However, the Western Roman Church soon reversed the direction. This relatively minor difference was mentioned as a factor in the Great Schism between the Orthodox and Catholic Christians in the eleventh century.