When asked, I give a variety of answers--some better than others. Recently I came across an apologia for facing the Lord (tabernacle) when celebrating Mass written by Dom Mark Kirby, a monastic priest in the Catholic Church in Tulsa OK. Reading through them, I agree with all of the advantages that Fr Mark lists. Perhaps others can add to the list.
What are the advantages of standing at the altar ad orientem, as I have experienced them over the past two years? I can think of ten straight off:
1. The Holy Sacrifice of the Mass is experienced as having a theocentric direction and focus.
2. The faithful are spared the tiresome clerocentrism that has so overtaken the celebration of Holy Mass in the past forty years.
3. It has once again become evident that the Canon of the Mass (Prex Eucharistica) is addressed to the Father, by the priest, in the name of all.
4. The sacrificial character of the Mass is wonderfully expressed and affirmed.
5. Almost imperceptibly one discovers the rightness of praying silently at certain moments, of reciting certain parts of the Mass softly, and of cantillating others.
6. It affords the priest celebrant the boon of a holy modesty.
7. I find myself more and more identified with Christ, Eternal High Priest and Hostia perpetua, in the liturgy of the heavenly sanctuary, beyond the veil, before the Face of the Father.
8. During the Canon of the Mass I am graced with a profound recollection.
9. The people have become more reverent in their demeanour.
10. The entire celebration of Holy Mass has gained in reverence, attention, and devotion.