A couple of questions from an interested non-Catholic...
How do you make the sign of the cross and when is it appropriate to do so? I've watched people do it over the years and they do it so quickly that it's difficult to follow.
Touching your forehead: "In the name of the Father"
Touching your chest: "And of the Son"
Touching your left shoulder: and of the Holy"
Touching your right shoulder: "Spirit."
Folding hands: Amen
Some cultures will switch the shoulders and go from right to left. Also Hispanics bring their hand back up to the lips before folding them. (I'm not an expert on the Hispanic part, so maybe someone else can check in with more to this detail.)
From The Catholic Encyclopedia [I've supplied the Latin translations. Hey, 4 years of Latin in High School was good for something! :-)]:
Sign of the Cross
A term applied to various manual acts, liturgical or devotional in character, which have this at least in common: that by the gesture of tracing two lines intersecting at right angles they indicate symbolically the figure of Christ's cross.
Most commonly and properly the words "sign of the cross" are used of the large cross traced from forehead to breast and from shoulder to shoulder, such as Catholics are taught to make upon themselves when they begin their prayers, and such also as the priest makes at the foot of the altar when he commences Mass with the words: "In nomine Patris et Filii et Spiritus Sancti"[In the Name of the Father, and of The Son, and of the Holy Spirit]. (At the beginning of Mass the celebrant makes the sign of the cross by placing his left hand extended under his breast; then raising his right to his forehead, which he touches with the extremities of his fingers, he says: In nomine Patris; then, touching his breast with the same hand, he says: et Filii; touching his left and right shoulders, he says; et Spiritus Sancti; and as he joins his hands again adds: Amen.) The same sign recurs frequently during Mass, e.g. at the words "Adjutorium nostrum in nomine Domini" [Our Help is in the Name of the Lord}, at the "Indulgentiam" after the Confiteor, etc., as also in the Divine Office, for example at the invocation "Deus in adjutorium nostrum intende" [O God, come to my assistance], at the beginning of the "Magnificat", the "Benedictus", the "Nunc Dimittis", and on many other occasions.
Another kind of sign of the cross is that made in the air by bishops, priests, and others in blessing persons or material objects. This cross recurs also many times in the liturgy of the Mass and in nearly all the ritual offices connected with the sacraments and sacramentals. A third variety is represented by the little cross, generally made with the thumb, which the priest or deacon traces for example upon the book of the Gospels and then upon his own forehead, lips, and breast at Mass, as also that made upon the lips in the "Domine labia mea aperies" [Lord, open my lips} of the Office, or again upon the forehead of the infant in Baptism, and upon the various organs of sense in Extreme Unction, etc.
Thank you for posing an excellent question! As a Roman Catholic (Western Church) attending a Maronite Catholic liturgy (Eastern Church), I have also seen some parishioners make the sign of the cross and then bring their right hand up to their lips. Here is an historical perspective.
The Sign of the Cross is not traced on the body in the same way by all Eastern Christians. At the words, "... and of the Holy Spirit," the majority of Eastern Christians move the hand horizontally from the right shoulder to the left. This was the universal custom of the Catholic Church, East and West, into the Middle Ages. For example, Pope Innocent III in the 13th century directed that the sign of the Cross be traced in this way by all Catholics, with two fingers and the thumb of the right hand joined (see the New Catholic Encyclopedia [1967], p. 479). Sometime later in the West, the direction was reversed to movement of the hand from the left to the right.
The joining of two fingers and the thumb was a reaction to the Monophysite heresy, which denied the two natures of Christ, signified by the two fingers. With the addition of the use of the joining of the thumb and two fingers the Trinity is signified. This heresy began in the Syriac Antiochene area. Since Maronites defended the true teachings regarding the natures of Jesus, they restored the practice of making the Sign of the Cross with the two fingers and the thumb joined.
The Sign of the Cross is made at the beginning and end of all prayers. In the Maronite liturgy, it is also the response given when the priest blesses the congregation throughout the liturgy, using the Book of the Gospels, the Consecrated offerings and the handcross.