The Christian sign of the cross was originally made with the right hand thumb and across the forehead only. The custom is attested to as early as the second century.Vestiges of this practice remain: some Christians sign a cross on their forehead to hear the Gospels during Mass; foreheads are marked with an ash cross on Ash Wednesday; holy oil (called chrism) is applied on the forehead for the sacrament of Confirmation. Around year 200 in Carthage (modern Tunisia, Africa), Tertullian says: "We Christians wear out our foreheads with the sign of the cross". It is thought that by the end of the second century Christians signed the cross on their forehead before taking any risk, such as embarking on a journey.
By the fourth century, the sign of the cross involved other parts of the body beyond the forehead. By the sixth century, these variations of smaller signs across the body became the one larger sign used now.
Read more about the sign of The Cross.
