Corporate Healing in the Liturgy
In times of persecution, early Christians needed some swift inconspicuous gesture to identify themselves to one another. Since a Christian is one who follows Christ, the challenge of Christ himself suggested the gesture to be used: "If anyone would come after me, he must...take up his cross and follow me" (Mk 8:34). Thus the sign of the cross, a secret gesture at first, later became an open publish act of professing the Christian faith.
Body language bespeaks externally what is present internally. Religious gestures in body language (kneeling, standing up genuflecting, praying with hands folded or uplifted, or striking one's breast) express various attitudes of relating to God. But body language in the sign of the cross externally expresses (professes) multiple facts of Christian belief: belief in Jesus' death on the cross, by which we were redeemed (see Colossians 2:13), by which Jesus crushed the powers of hell (v.15). It expresses belief in the Incarnation - for only as a human, could God die on the cross (see Hebrews 2:14); and belief in the Trinity, invoked verbally with the action. It depicts our intent to enter into Jesus' pascal mystery by dying to self with him and rising to a new life with him (see Romans 8:11; 11:15; Ephesians 2:5).
These basic Christian (not just Catholic) beliefs expressed by the sign of the cross make it a most sublime form of body language, a sign of the times, for all times, and all Christians.