The Altar Curtain (or Altar Veil) is a linen which is drawn behind the Holy Doors of the Iconostasis (Icon Screen) and aides in the ritual separation of the Sanctuary (Holy Place) from the Nave.  It is reminiscent of the veils which separated the Sanctuary and Holy of Holies in the Old Testament Jewish Temples.  Even in the Gospel accounts, we hear about the tearing of these veils upon the death of Christ on the Cross.  The inclusion of such curtains in Christian worship is common to variety of traditions, including the Byzantine tradition.

Where did it come from?

Early Christians understood themselves as the inheritors of the religious tradition passed onto them by their Jewish forebears.  Christ was Jewish and all his Apostles were Jewish, with Gentile followers quickly coming into the fold after the Resurrection.  As such, while Christianity would go on to grow into its own unique expression of the faith as handed down by the descendants of Adam and Abraham.  Therefore, in Christianity, especially in the Catholicism and Orthodoxy, much of our religious practices and nomenclature look very Jewish.  One of the reasons we maintain the use of Old Testament scripture is because we recognize a spiritual continuity with that tradition.  When Christianity began to move out of home Churches and into larger temples for public worship, developments which harked back to the old Tent of Meeting (Exodus 36:8- 38:20) and the Temple of Solomon (1 Kings 6:1-38 and 7:13-51) were not far behind.  One of the earliest versions of this was the Templon, a barrier which separated the clergy in the sanctuary from the laity in the nave.  This would develop into the Iconostasis with Curtain which we are familiar with today.

What does it mean?

Apart from having a cosmetic similarity to the old Jewish Temple, the Altar Curtain is another example of how the Byzantine tradition emphasizes the aspects of mystery and covering of sacred things in our spirituality.  While God has made Himself manifested to us in the Incarnation, there is still much about Him which is beyond our comprehension and even set apart from our own perceptions, just like in the Old Testament context.  Bearing in mind also that we are not merely the people of the Old Covenant but also of the new, the opening of the Curtain is a unique feature to Christianity.  Where before the Curtain was always closed to the people, now the Curtain is torn open by the Passion of Christ (Matthew 27: 45-56, Mark 15:33-41, and Luke 23:44-49).  The Curtain emphasizes the mysteries of God in its concealing of the Sanctuary and accentuates God reveling Himself to us every time it is drawn open, especially during Pascha where the Curtain is fully opened for all of Bright Week.

Why have we never seen it before?

While the inclusion of an Altar Curtain is not universally done on a pastoral basis, varying from parish to parish, it is nonetheless a part of the received liturgical traditions of our Byzantine Catholic Church.  In 1944, a commission from the Sacred Congregation of the Eastern Churches in Rome published and promulgated, among many others, two books which discussed the practice and implementation of liturgy and worship in our Church:

The Ordo Celebrationis: The Order for the Celebrations of Vespers, Orthros and the Divine Liturgy According to the Ruthenian Recension

and the

Instruction for Applying the Liturgical Prescriptions of the Code of Canons of the Eastern Churches.

The purpose of these books was to outline the attributes of our Ruthenien expression of our Byzantine Catholic faith.  Among these texts are frequently mentioned of the use of the Altar Curtain as a preferred included element in our worship spaces.  In the United States, many of our people rejected their inclusion (even rejecting the inclusion of the Icon Screen as a whole) for a variety of reasons.  Despite these objections, nothing has changed in the formal position of our particular church, which is to have a preference for involving all aspects of our liturgical life, including the Altar Curtain.