A wonderful explanation of the beautiful sacramental and Sign of our Faith:
The Sign of the Cross
The most basic Christian gesture in prayer is and always will be the Sign of the Cross. It is a way of confessing Christ crucified with one's very body, in accordance with the programmatic words of St. Paul: "[W]e preach Christ Crucified, a stumbling block to Jews and folly to Gentiles, but to those who are called, both Jews and Greeks, Christ the power of God and the wisdom of God" (1 Cor 1:23). Again he says: "I decided to know nothing among you except Jesus Christ and him crucified" (2:2).
To seal oneself with the sign of the Cross is a visible and public Yes to him who suffered for us; to him who in the body has made God's love visible, even to the utmost; to the God who reigns not by destruction but by the humility of suffering and love, which is stronger than all the power of the world and wiser than all the calculating intelligence of men.
The sign of the Cross is a confession of faith: I believe in him who suffered for me and rose again; in him who has transformed the sign of shame into a sign of hope and of the love of God that is present with us. The confession of faith is a confession of hope: I believe in him who in his weakness is the Almighty; in him who can and will save me even in apparent absence and impotence.
By signing ourselves with the Cross, we place ourselves under the protection of the Cross, hold it in front of us like a shield that will guard us in all the distress of daily life and give us the courage to go on. We accept it as a signpost that we follow: "If any man would come after me, let him deny himself and take up his cross and follow me" (Mk 8:34).
The Cross shows us the road of life-the imitation of Christ. We connect the sign of the Cross with confession of faith in the triune God-the Father, the Son, and the Holy Spirit. In this way it becomes a remembrance of Baptism, which is particularly clear when we use holy water with it. The Cross is a sign of the Passion, but at the same time it is a sign of the Resurrection. It is, so to speak, the saving staff that God holds out to us, the bridge by which we can pass over the abyss of death, and all the threats of the evil one, and reach God. It is made present in Baptism, in which we become contemporary with Christ's Cross and Resurrection (cf. Rom 6:1-14).
Whenever we make the sign of the Cross, we accept our Baptism anew; Christ from the Cross draws us, so to speak, to himself (Jn 12:32) and thus into communion with the living God. For Baptism and the sign of the Cross, which is a kind of summing up and re-acceptance of Baptism, are above all a divine event: the Holy Spirit leads us to Christ, and Christ opens the door to the Father. God is no longer the "unknown god"; he has a name. We are allowed to call upon him, and he calls us. Thus we can say that in the sign of the Cross, together with the invocation of the Trinity, the whole essence of Christianity is summed up; it displays what is distinctively Christian.
Joseph Cardinal Ratzinger (Now Pope Benedict XVI)—“Spirit of the Liturgy”