Dear Mike Et al,
You have mentioned:
"The iconostasis is a barrier between the narthex and the altar. It was introduced after Christianity became state religion in Roman Empire and number of faithful improved enormously. It kept those not-so-right people out of the sanctuary."
I think this to be a rather theologically problematic perception insofar as many of us are not quite so right so to speak. If look at things liturgically, what we are doing, where we are and most importantly why, we can see things differently. Christianity becoming a state(s) religion and the Churches increased numbers of faithful did not cause the Church to put up the iconostasis as a barrier, for the barrier has been breached via the incarnation. We see this in the Church at every Divine Liturgy, thanks be to Gods' love. The Church is our sovereign and the iconostasis reflects Gods' active love throughout the history of man.
Reflecting on the truth that Christ and His Bride, the Orthodox Church will always remain our true sovereign can be seen during the Liturgy. The Priest says; "Holy things are for the holy" before we receive the Eucharist, even when we might think, "Lord God, I'm not holy etc." The Priest cries out; "In the fear of God with faith and love come forward." So on the one hand the Church is saying that holy things are for the holy even though I fall short, on the other hand is the Bishop or Priest holding the Chalice. Christ and the Church are both militant and triumphant as reconciliation happens within the Church even when we know we are falling short.
It is the operation of the Holy Spirit, the helper, the comforter whom the Father sends in Christ's name that makes up for that which might be lacking in us. We can see the good shepherd, Christ whose yoke is easy and whose burden is light, that is within the radiant Church.
Shine, shine new Jerusalem! For the glory of the Lord has dawned over you. Dance now and be glad, Sion; as for thee, pure One, rejoice in the resurrection of your child.
There is joy for us. A friend of mine not long ago responded to some questions regarding the iconostasis, he summed things up much better than I can below.
"There is quite a lot of symbolism to the division of the church into altar and nave, with the separation formed by the iconostasis. Indeed, that symbolism varies from service to service, and indeed through parts of services, being called upon to witness to different things at different times. But surely the basic reality you've mentioned - of earth and heaven - is an overriding symbol.
The division of the sacramental space between that representing earth and all creation, and that representing heaven, God and the angelic realms, is not meant to indicate a barrier between these two realms (keeping in mind that we have icons of heavenly things outside the altar, and icons of human things within it; indeed, icons themselves are a meeting place of both). The division of space is meant to realise symbolically their encounter. It is by having the altar separated from the nave by a noted wall (the iconostasis), that this barrier can be used to symbolise not just a divide, but also a breaking of the divide. The Royal Doors can be closed to symbolise anticipation of the coming of salvation (hence the talk of the icons on the doors themselves, as above in this thread), and can be opened to indicate the real presence of that salvation. The symbolism of the barrier is important at, for example, the reading of the Gospel, which is brought out of the altar, into the midst of the nave - the Word of God coming into the cosmos, just as Christ came into the world; a 'breaking of the divide' that sin constructs between man and God. So, too, later in the Divine Liturgy, all the doors and even the curtain are closed when the priest elevates the gifts and proclaims 'The holy things are for the holy': reminding us, through those closed elements, of our utter break from holiness through our sin. But moments later, the doors open and the chalice - the Saviour himself - comes through that divide; a meeting of the heavenly and the earthly.
The point of having the iconostasis as division is that it allows the reality of the breaking of that divide, or better, the healing of that divide, to be made visible in the liturgical symbolism of the Church. Without the iconostasis (or some manifestation of it), this important reality of Christian life is made less immediate to the experience of worship. Perhaps one of the best ways to recognise this, is to think on Bright Week - the week immediately following Pascha. During this period, all the doors on the iconostasis are left open at all times (including the side, or 'deacon's', doors, which are normally never left open), symbolising that in the resurrection the bonds of death that divide man from God have been ultimately and triumphantly defeated. This is always a very noticable, meaningful liturgical act, the leaving open of these doors; but it has that impact, that degree of forceful reminder of the reality of unity enabled through the resurrection, only because normally the doors are kept closed, opened at significant moments in various services. It is because of the liturgical symbolism of that 'divide', that one comes to appreciate so immediately the reality of its breach.
There are also other things that the iconostasis and the doors symbolise, in various moments of the worshipping life of the Church. At vespers, for example, the whole of the iconostasis, and the Royal Doors in particular, are often seen to symbolise the gates of Eden, out of which Adam has been cast on account of his sin. So the priest comes out wearing only his cassock and epitrachilion (the sign of his office, which he must wear to serve any service), head uncovered -- a symbol of Adam standing naked before the doors of Eden, looking back in at that which he has abandoned through his transgression; while through this the reader intones Psalm 104 (103 LXX), which is a psalm on the mystery of creation ('The waters run above the hills... the lions roar about their prey, seeking their food from God... how manifold are Thy works, O Lord, in wisdom Thou hast made them all', etc.). So we have a liturgical image of our exile from paradise on account of our sin: a dark church, a closed gate, a 'naked' priest/Adam, and readings leading from this psalm of creation into the larger reading if the psalter, to the supplication ('Lord, I have cried to Thee: hear me...'). Finally, the priest re-emerges, now in all his vestments, and the gates of Eden are opened as the choir sings 'O Jesus Christ, Thou gentle light...': a visible, liturgical act that demonstrates the healing of the disunion of sin by Christ. Once again, without that 'divide' given physical iconic form in the iconostasis, this liturgical engagement would be much lessened."