The curtain that is drawn across the Royal Doors of the iconostasis in an Orthodox Christian temple is a representation of the curtain that separated the Holy of Holies in the ancient Temple of the Jews in Jerusalem. During the Divine Liturgy the curtain is drawn closed after the Great Entrance, to remain closed until the reciting of the Creed, as the priest commemorates the sacrifice of our Lord Himself for the atonement of the sins of mankind as did the high priest of the Temple with expiatory sacrifice for his own sins with blood of animal sacrifices.
The curtain is not used universally in the Orthodox Christian Church.
The significance of the curtain is presented by the Apostle in Hebrews 9, as he recalls the special ceremony held in the Temple of the Jews in Jerusalem on Yom Kippur, the "Day of Atonement." In the Temple, a room was set aside behind a curtain called the Holy of Holies into which only one person, the high priest, could enter and then only once each year, on the Day of Atonement. On that day, after offering special sacrifices, the high priest collected in a bowl some blood from the animal victims and carried it behind the curtain, into the Holy of Holies. In a ritual that symbolized the people's repentance for the sins of the previous year and to entreat God's forgiveness he sprinkled the blood about the chamber. As the high priest was only a man, he had to offer the expiatory sacrifice for his own sins, and because he continued to sin, he had to offer the sacrifice year after year. Apostle Paul tells us that this ritual was a prophecy of the incarnation, death, and resurrection of our Lord.
During the Divine Liturgy, bread and wine are carried to the altar table at the Great Entrance to begin our offering of the Eucharist, the sacrifice that reaches its climax in the invocation of the Holy Spirit upon the Gifts and culminates in our partaking of them, now transfigured by the Spirit's grace and power into the crucified and risen Body and Blood our Lord Jesus Christ. As soon as the bread and wine are placed on the altar table, the royal doors are closed and the curtain is drawn across the opening, to remain closed until the Creed. The significance of this action is made clear in a phrase from the prayer the priest reads while the curtain is closed. He asks God to "accept also the prayer of us sinners, and bear it to Thy holy altar, enabling us to offer unto Thee gifts and spiritual sacrifices for our sins and for the errors of the people." The last words echo those of the Apostle in Hebrews 9:7 and link our offering of the Gifts to his discussion of the Jewish ritual of atonement, recalling the special ceremony held in the Temple of the Jews on the Day of Atonement.
In the Christian offering, the priest offers the sacrifice of that of our Lord who as the eternal Word of God become man and took to Himself everything which is human, even the consequences of sin, He is sinless Himself. By His crucifixion and resurrection, He offers the supreme and perfect sacrifice, His pure and unstained Self. His sacrifice is complete — thoroughly purging the sins of mankind - because He does not need to offer it first for His own sin. He presents this offering, not on a mundane altar, but in heaven itself, before the Throne of the Father, which He Himself shares, together with the Holy Spirit (Hebrews 9:11-12).
Unlike the Jewish high priest, Christ does not complete the atonement alone. As He enters the heavenly Temple our Lord bears with Him His humanity, which He shares with us. Thus, we enter the Holy of Holies with Him, borne into the glory and peace of the Kingdom by His purity and love. Our Lord's great sacrifice brings us remission of sins and sanctification by the power of the Holy Spirit and entrance into the Kingdom. The words of the prayer link our offering of the Gifts with Christ's entering "into the inner shrine behind the curtain" (Hebrews 6:19), "by the new and living way which he opened for us through the curtain, that is, through His flesh" (Hebrews 10:20).
In each Liturgy we unite ourselves with our Lord's sacrifice and we enter heaven with Him. On the people's behalf the priest carries bread and wine into the altar, behind the closed curtain of the royal doors, like the Old Testament priest symbolizing the Passion and rising of the incarnate Christ. With the curtain of our temple closed, the faithful prepare to receive the Body and Blood of the living Christ. St. John Chrysostom declares, "With this Blood not Moses but Christ sprinkled us, through the word which was spoken; 'This is the Blood of the New Testament, for the remission of sins.'