Why is the perpetual virginity of Mary important in Eastern Orthodoxy? I am looking into the Eastern Orthodox church, and was wondering why believing that Mary was a perpetual virgin was an important belief? Now I don't have a real problem if tradition holds that she was a perpetual virgin, and then it makes sense as some sort of historical fact about Mary. But it seems like the belief is more important than just historical fact.  There are many prayers to the Theotokos (Mary) that refer to her as "ever virgin." If church tradition held that Jesus had blue eyes, I would have no reason to doubt it, but I wouldn't insert "oh blue eyed one" into my prayers to Jesus.

If Mary had married Joseph and then had sexual relations within her holy marriage, there is nothing sinful or less worthy about her in my mind. The impression I am getting is that perhaps celibacy is seen as a higher calling than marriage, and I don't think I believe that is true to the Gospel. Being celibate might be a calling for some, like Paul, who needed to be away on travels a lot, and wouldn't be there for a family were he to get married.  But we can be faithful to God in our local communities as well (such as our local priest) and his mission is no less important than the ministry of the celibate man.
Among other things, the Ever-Virginity of the Theotokos is understood to be the fulfillment of a prophesy by Ezekiel (44:2)1:


  This gate shall be shut, it shall not be opened, and no man shall enter in by it; because the LORD, the God of Israel, hath entered in
  by it, therefore it shall be shut.


This meaning is ascribed to the verse by a number of Church Fathers, included Methodius of Olympus2 (d.311), Cyril of Alexandria3 (378-444), Jerome4 (347-420).  The Ever-Virginity of Mary was a pervasive doctrine of the first millennium Church, as witnessed by John of Damascus (676-749) in his summary of the Faith, An Exact Exposition of the Orthodox Faith:


  The ever-virgin One thus remains even after the birth still virgin,
  having never at any time up till death consorted with a man. For
  although it is written, And knew her not till she had brought forth
  her first-born Son [Matthew 1:25], yet note that he who is
  first-begotten is first-born even if he is only-begotten. For the word
  “first-born” means that he was born first, but does not at all suggest
  the birth of others. And the word “till” signifies the limit of the
  appointed time but does not exclude the time thereafter. For the Lord
  says, And lo, I am with you always, even unto the end of the world
  [Matthew 18:20], not meaning thereby that He will be separated from us
  after the completion of the age. The divine apostle, indeed, says,
  And so shall we ever be with the Lord [1 Thessalonians 4:17], meaning after the general resurrection.5


John continues with an explanation which underlines why it is unacceptable within Orthodox doctrine to accept that the Virgin did not remain so after the Nativity: "For could it be possible that she, who had borne God and from experience of the subsequent events had come to know the miracle, should receive the embrace of a man. God forbid!"

The above explains, I think, why the ever-virginity of Mary is an important belief, but it perhaps does not explain why the accolade of "Ever-Virgin" is frequently included in the prayers of the Church.

Although it is certainly possible to look upon the texts of Orthodox Services as nothing more than scripts for the choir, they actually serve a much deeper meaning.  Each Orthodox Service can be seen as a theological lesson.  Metropolitan Hilarion Alfayev states:


  The theological authority of liturgical texts is, in my opinion, even
  higher than that of the works of the Fathers of the Church, for not
  everything in the works of the latter is of equal theological value
  and not everything has been accepted by the fullness of the Church.
  Liturgical texts, on the other hand, have been accepted by the whole
  Church as a “rule of faith” (kanon pisteos), for they have been read
  and sung everywhere in Orthodox churches over many centuries.
  Throughout this time, any erroneous ideas foreign to Orthodoxy that
  might have crept in either through misunderstanding or oversight were
  eliminated by Church Tradition itself, leaving only pure and
  authoritative doctrine clothed by the poetic forms of the Church’s
  hymns.6


Arguably, Jesus having had blue eyes - which receives no mention whatsoever in Scripture or the writings of the Fathers - does not merit the sort of theological lesson of sorts as does the Ever-Virginity of the Theotokos.  You will find similar theologically-laced accolades for other things throughout the service books.  God is repeatedly referred to with the prefix "all merciful" or sometimes with the suffix "the lover of mankind".  The Apostles are called "praiseworthy" or "wise".  Sometimes the Theotokos is referred to as "all-pure".  All these things are little reminders of Orthodox doctrine that are heard throughout the service.



1  Elder Cleopa of Romania, The Truth of Our Faith
, p.87
2  Oration concerning Simeon and Anna
3  Commentary on the Gospel According to St. Luke, Sermon I
4  Letter XLVIII, 21; also Against Pelagius II
5 Book IV, Chapter XIV
6 Orthodox Worship as a School of Theology