The Sign of the Cross is a symbolic ritual gesture which marks the four points of the Cross on Calvary over one's body. It also represents loving God with all one's heart, soul, mind and strength. The sign of the cross is most often made at the name of the Holy Trinity, to show reverence for a saint, holy object, or person, at the beginning or end of a prayer, to show humility or agreement, or on numerous other occasions which may vary slightly according to regional/ethnic practice or personal piety. Some Orthodox may make the sign of the cross a hundred or more times during a Divine Liturgy or lengthy service.
In general Orthodox practice, the right hand is used. The thumb, index, and middle finger are brought to a point. They are then placed on the forehead after that moved down to the sternum. Finally the hand is moved to the right shoulder and horizontally across to the left. Oriental Orthodox and Western Christians, however, go in reverse order on this last step, from left to right. As one moves through the Sign, one recites, at the forehead, "In the name of the Father"; at the sternum, "and of the Son"; and across the shoulders, "and of the Holy Spirit, Amen." There are variations that occur. For example, some may mark a very large cross, or a very small one. Some may say "and of the Holy Spirit" across the shoulders. After moving the hand from one shoulder to the other, it may return to the sternum. It may be accompanied instead at times with the words of the Jesus Prayer in some form, or simply "Lord have mercy".
The thumb, index and middle finger brought to a point symbolize the Trinity, three persons sharing a single essence. The remaining two fingers are kept pressed close together and to the palm, representing the human and divine natures united together in Jesus Christ.
There is no dispute over the centrality of the Cross in the spirituality and understanding of the Church. The first definitive written records of Christians “making the sign of the Cross” come from the late 2nd and early 3rd centuries. Scholars have long noted that practices/beliefs were assumed and already well in effect (like the Scriptures) by the time they were in written form.
The current evidence is that the sign of the Cross was traced with one finger (most likely the thumb) on the forehead (and over the mouth when reading Scripture) and over anyone or anything Christians wished to consecrate. The Cross was traced with the right hand (unless one was disabled, etc.), which itself symbolized intimacy with the Christ “who sits at the right hand of God.”
The making the sign of the Cross on one’s forehead corresponds with the ancient cultures of the Scriptures (e.g. Genesis 4; Ezekiel 9). Marks on the forehead conspicuously display and proclaim the spiritual condition or identity of the person as seen and identified by God. Phylacteries (small leather pouches with symbols of the Torah inside them) were worn around the right hand and forehead of the pious Jew. In the New Testament, marks on the forehead or right hand identified people with God or alignment with the antichrist. On the forehead of martyred Christians (Revelation 14 & 22), it symbolized the very Name of God Himself. It was easy to equate making the sign of the Cross on the forehead with the Greek letter “X” (chi - the first letter of the name of Christ in Greek) as it was made with the same gesture.
By the 4th century, the sign of the Cross began to be traced by two (the index and middle) fingers. It also reflected how bishops or (beginning with the 4th century) presbyters (when they began to function as priests) blessed others; the classic Roman gesture for public speaking was the two fingers extended. By the 8th century, the two fingers came to symbolize the two natures of Christ and to distinguish Christians in the East under Islamic rule from Muslims who, as some sources from that time show, lifted “one finger when asking Allah for forgiveness.”
Evidence from the 8th century shows the shift of tracing the sign of the Cross to over the body in the wake of the Iconoclastic Controversy. In destroying/removing icons from churches, the iconoclasts replaced them with paintings/mosaics of large Crosses (usually a major sized one in the apse of the Altar), a symbol with which all, iconoclasts and iconophiles (lovers of icons), could agree. With no icons in the churches, other symbols (like the making of the sign of the Cross) were greatly magnified by iconoclasts to show that they were not trying to be impious. While Iconoclasm was heretical, the symbol of the Cross was not. After the controversy ended with the Seventh Ecumenical Council (787), iconophiles continued the practice of tracing the sign of the Cross over the body (head to heart to shoulders—right to left, as when traced on the forehead, in both East and West) with the two fingers.
By mid 9th century the “three fingers” are replacing the “two finger sign” (though in the East it did not become universal until after the 17th century following the Old Believer Schism in Russia), expanding the focus that through the crucified Jesus we enter communion with the Holy Trinity. In the 13th century in the West, we have the first mention of some who “make the sign of the Cross from the left to the right,” the reasons varying from crossing from misery (left) to glory (right) to mirroring the priest blessing them. Oriental Orthodox Christians (Coptic, Armenian, etc.) cross themselves left to right, seeing the meaning as praying that they not be on the left but on the right of the Judgment Seat (whether this developed independently or as a result of later Western/Latin influence is, as of yet, historically unclear). Later centuries would see the West become universal in not only crossing from left to right but also in changing from using the three fingers to using the whole (open) hand.
Regardless of how the Cross was (is) traced in the various traditions, the Church has understood its expression as concretely identifying oneself with the Lord who, through His crucifixion, fully participates in our humanity, which then, as seen in the resurrection-ascension, brings us to organically participate in the life of the Trinity. The Cross symbolizes (“brings together”) God’s organic descent into death and darkness, through which we are given back to Him. It also symbolizes our embracing the spiritual battle within the deserts of our hearts and choosing to see things from the perspective of the God who shows His all-powerful and sovereign Love by giving up control of His very life on the Cross.
Use of the sign
In Eastern Orthodox prayers, the sign of the cross is usually made whenever all three persons of the Trinity are addressed, or even alluded to. Before commencing any prayer, in fact, the Sign is typically made. Upon entering a church, and the sanctuary within the church, one will make the Sign partly as an outward sign of reverence and veneration. Orthodox laymen will make the Sign as one way of venerating an icon; Priests have many more specific occasions upon which to make the Sign. Many members of the Faith will make the Sign in a way that may seem idiomatic to some: for example, if a member is exposed to blasphemy, he or she may make the Sign, partly to suggest subtly and politely to the speaker that an offense has been committed. Some members of the Faith will use the Sign in what almost appears to be a wish for luck; it may be that, or a part of an unsaid prayer for God's blessing, as when beginning a journey or a sports competition.
The Sign of the Cross has minor variants as well: it can be made in the air to bless objects, and it may trace a very small trajectory, such as on the forehead (as the earliest descriptions of the Sign suggest). For a member of the Faith, perhaps the essential element of the Sign is that it physically indicates the direct relevance of the Cross, of the Sacrifice of Jesus, to one's person or surroundings. It is an engagement of the body that affirms what the faithful professes. It is also a sign to others of what one professes.