The sign of the cross came down to us from very early Christianity with nothing clear as who started it. However, here are some facts regarding its practice among early Christians.
Tertullian, a Carthegenian, was the first Christian author to write in Latin. His surviving works dated from 196 AD to 212. Regarding the sign of the cross, he wrote: "Wherever we go, in getting out or coming in; when we put on our clothes or our shoes; whether we eat or we prepare to go to bed or whatever we do, we sign ourselves with sign of the cross."
St Ephraem who died sometime in 373 AD, was the only Syrian Doctor of the Church. About the sign of the Cross, St Ephraem wrote: "My son, see to it that whatever you do, your work is marked by the life-giving sign of the Cross. Never forget this, whether you eat or drink, or when you go to sleep; whether at home or when you are in a journey. There is no better behavior to compare with this. make this as a protection in all that you do. And teach this to your children that, they too would learn of it." This is fundamental to early Christians.
St Paul wrote to the Galatians: "But God forbid that I should glory save in the cross of our Lord Jesus Christ". (Gal 6:14) Of course this means Christ's sufferings. But we cross ourselves to remind ourselves of the sufferings of Jesus. There are even some who say that the sign of the cross is hinted in Revelation as "the seal of the living God" (5:2) or "his Father's name written on their forehead" (14:1) or even the mark of salvation in Ezekiel 9:4, as the sign of the Cross is used in baptism, the sacrament of invitation to Christianity.
The sign of the cross, in words and in action, reminds us of the two central realities of our faith: who God is (the Trinity) and what God has done for us (the Cross). These are the core of why Catholics do the sign of the cross.
From the earliest days of the Church, Christians understood that the cross of Christ has great power. Even the sign of the cross is powerful because it is a reminder of the instrument Jesus used to defeat Satan. Tertullian recommended that the faithful mark themselves with the sign of the cross at all times because of its power in bringing Jesus' sacrifice into their daily lives.
St. Cyril of Jerusalem expresses the power of the Cross very well: "Be the Cross our seal made with boldness by our fingers on our brow, and on everything; over the bread we eat, and the cups we drink; in our comings in, and goings out; before our sleep, when we lie down and when we rise up; when we are in the way, and when we are still. … It is the Sign of the faithful, and the dread of devils… for when they see the Cross they are reminded of the Crucified; they are afraid of Him, who bruised the heads of the dragon." (Catechetical Lecture 13)
The sign of the cross is a powerful way of making us mindful of the Trinity and inviting God into our prayer and into our daily lives. It brings the power of Christ's cross to us and can be a powerful help against temptation and an excellent way of reminding us of the great things Jesus has done for us. Pray the sign of the cross often and be mindful of what it means in the life of the Church and in your own life!
Fr. Antonius David Tristianto, O.Carm.