The Orthodox Church accepts virgin Mary as truly Theotokos and preaches her ever virginity; i.e. that she stayed a virgin, not only during the birth of Christ, but afterwards as well.
Virgin Mary did not of course give birth to the divine nature of Christ. However, in her bosom God was truly united to man, the divine and the human nature. Thus virgin Mary became the laboratory of the Theanthropos union and is truly Theotokos (Luke 1:35. 43. 68. 76, c.f. Malachi 3:1).
Christ did not have two faces, but one. For this we claim that that which happens to one of His natures, happens to Him Himself; whatever happens to His body happens to Him Himself, for it was truly His body (c.f. Acts 20:28). Thus, we confess that virgin Mary became truly "mother of the Lord", i.e. true Theotokos (Luke 1:43).
If mother Virgin is not Theotokos, if, that is, God was not united in her bosom with man, man's salvation was not realised, for "the one not taken on is also unremedied" ("το απρόσληπτον και αθεράπευτον"). If man was not received totally by the divine nature of Christ, if he did not unite to God "without confusion and without change" in the one face of Christ, then Christ did not save man. For this reason the Church insists on the term Theotokos.
The Orthodox Church also accepts Mary as ever virgin. In the Hebrew text of the Old Testament it is mentioned: "For I was my father's son, tender and only beloved in the sight of my mother" [This is the KJV translation; a much better translation from the Vulgate is the following: "For I also was my father's son, tender and as an only son in the sight of my mother"] (Proverbs 4:3). Of course, Solomon here does not refer to himself, for he himself was not only-begotten (2 Sam./2 Kings 11:27. 12:24).
Prophet Isaiah calls her "the virgin" (Isai. 7:14. Matth. 1:23) and Ezekiel calls her "gate", that was and stayed 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" (Ezek. 44:1-3); that which Christ uses wants it only for his own use (c.f. Mark 11:2. John 19:41).
Righteous Joseph was given to virgin Mary with the purpose of protecting her; in order to be "her husband" in the law and for her to be "wife" of his according to the law (Matth. 1:19-20), exactly in the same way that Joseph was, according to the law, "father" of Jesus (Luke 2:27. 41. 48-49. John 6:42); but not natural father of His (Matth. 1:18-20). After all, the virgin is mentioned as "spouse" of Joseph's (Matth. 1:18. Luke 1:27. 2:5). In fact, after Christ's birth Joseph is no longer called Mary's "husband" (Matth. 2:11-14. 19-21).
Those that reject the ever virginity of Theotokos, refer to some verses from the holy Bible, which they misinterpret; they do not understand them in the way they were interpreted by the Church (1 Tim. 3:15).
The "And he knew her not till she had brought forth her firstborn son" (Matth. 1:25) is mentioned regarding all that took place before the birth. The holy Bible here wants to secure Christ's birth via the Holy Spirit; without discussing what took place afterwards (c.f. Matth. 28:20. 1 Tim. 4:13).
The term "prototokos" ("firstborn") does not imply that other children followed; it means the first born child, the one that "opens" the bosom of his mother, independently of whether other children followed or not (Exod. 13:2. Numbers 8:16. 18:15. 1 Kings 6:7. 10. 14 according to the O' (70)). In fact, the word "Prototokos" also means Almighty (Psalms 88:28/89:27).
The so-called "brothers" of Jesus (Matth. 12:46. 13:55-56. Mark 6:3. Luke 8:19-21. John 2:12. 7:3. 5. 10. Acts 1:14. 1 Corinth. 9:5. Galat. 1:19) were obviously "brothers" according to the law, in the same way Joseph was "father" in the law, and not brothers of Christ in flesh. After all, their behaviour towards Christ proves that they were probably older than him, something that excludes the possibility of relation in flesh, since Christ is called "prototokos".
But if Mary had so many children (at least six), would she accept to go to disciple John's home? (John 19:26-27); clearly Christ would not suggest something like that. James and Judas call themselves "servants", not brothers of Christ (James 1:1. Jude 1). They were not thus children of Mary; they were "brothers" of Jesus in the law. After all, the word "brother" in the holy Bible has a more general meaning (Gen. 12:5. 13:8. 29:12. 1 Omiss./Chron. 23:21-22).
St. Ambrosius (339-397 AD) says that Joseph "could not possibly offend the Temple of the Holy Spirit, the mother of the Lord, the bosom of the mystery" (Ambr.,Memorandum to Luke, 2, 6). The same is underlined by Chrysostom (Memorandum to Matth., Speech 5:3). Hieronymus characterises the rejection of the ever virginity "insult" against God and writes a relevant writing against the heretic Elbidius. Augustine stresses that virgin Mary was "virgin during conception, virgin during birth, and virgin till death" (Catech. 11, chap. 22,40).
The Orthodox Church honours virgin Mary. Already from the Old Testament her special place had been prophesied (Proverbs 29/31:29). She is "blessed among women" and she "found grace from God". Shaded by the Holy Spirit and from the Power of the Almighty, she is "mother of the Lord" and for this we must all honour her and bless her (beatitude) (Luke 1:28-48). In John's Revelation, a woman is presented dressed the sun, glorified with the almighty glory. This of course, is the Church, but at the same time symbolises virgin Mary (Revel. 12:1-6. 13-17). This is the one "more honourable than the cherubims and immensely more glorified than the seraphims". For she herself became throne of the Lord, whereas "above it stood" the seraphims i.e. they stood around His throne (Isai. 6:2).
Rightfully, the Orthodox Church calls virgin Mary Panagia; not of course in relation to God ("one Holy, one Lord ...") but in comparison to men and angels. She herself prophesied that all generations will pay respect to her (Luke 1:48). But the Orthodox Church does not worship virgin Mary. Worship belongs only to God.
St. Epiphanius counts among the heretics, those that deny the ever virginity of Mary and calls them antidicomarianites. On the other hand, he talks against those that would offer "collyris", a type of pie (collyrians) and worshipped virgin Mary, "in place of God" (Epiph., Against antidic. 14. 23). These heretics, Epiphanius says, were conducting "in the name of the holy virgin beyond a normal honouring, something not allowed and blasphemous" and conducted divine services "in her name via women, something that is completely disrespectful and preposterous ... devilish work and teaching of a dirty spirit" (Against antid. 23).
Therefore we see that St. Epiphanius' views cannot be turned against the honour to virgin Mary and to the saints. In fact, Polybius, who was Epiphanius' biographer, mentions that he used to visit at night the places where the relics of the holy martyrs were "and to pray to God for each one of the saddenned ones" (Life of Epiph., 53). Epiphanius underlines that "beyond what is necessary, do not honour the saints, but honour their Prelate" (Against antidic. 24). He was against the substitution of the worship of God with the worship of virgin Mary and of the saints; this is what his contemporary heretics would do!
The words of Christ, that mother and brother of His is whoever does the will of His Father (Matth. 12:50. Mark 3:35) is not offending to virgin Mary, for she was faithful to God's will. The "Yea rather, blessed are they that hear the word of God, and keep it" (Luke 11:28) means "yes, verily" (Rom. 10:18). Virgin Mary was blessed in this sense as well (Luke 2:51), for she was faithful to God's will. If the virgin was not pious, then clearly she would not be blessed, for it would not benefit her at all the fact that she gave birth to Christ. The "woman" (John 2:4) did not have a diminutival meaning in those times (John 4:21. 20:15).
Many protestant groups claim that the term Theotokos and the ever virginity are things insignificant and not essential. But, as we mentioned before, the Church of the first centuries does not agree with these opinions. For this reason, the third Oecumenical Synod (431 AD) secured the term Theotokos and characterised Nestor's didache as heretical. The same synod did not neglect to excommunicate Nestor himself and his followers.
The Orthodox Church rejects the immaculate conception of Virgin Mary, because she believes that only road to salvation is Christ (John 1:12-13, 14:6. Acts 4:12. 1 Corinth. 1:30-31). Christ became the "beginning" (1 Corinth. 15:21) and the "new creation" is realised only "in Christ" (2 Corinth. 5:17. Tit. 3:4-7).
Away from the Body of Christ there is
no salvation (Hebr. 2:14-15). This is the reason why the Orthodox Church rejects
the dogma of immaculate conception of Virgin Mary, i.e. of the teaching
that Virgin Mary was free from the consequences of Adam's sins since the time
of her own conception. Our Church stays put in this basic salvation-related
truth, which is expressed in the sentence: "the one not taken on is also unremedied".
(In case you wonder whether Virgin Mary had sinned during her life since her conception was not immaculate, we must make a point here. Until the age of 16, when she was "given" to Joseph in the law, she was in the temple of God and was even fed by an angel of God, and therefore she did not have any earthly images in front of her to bring thoughts to her that would lead her to sin. The only sin she committed was the one she was born with, Adam's. Now, when the angel of the Lord asked her if she will accept to be Mother of God and she accepted, i.e. during her Annunciation, she was mystically cleansed from the possibility of making any other sins henceforth in her lifetime, including the forefatherly sin, thereby the divine oeconomia ensuring not only a nature that was human, which was needed for Christ to unite with, but also a sinless one, from that moment onwards, which was needed to ensure that the Mother of the Lord would be sinless henceforth. In effect, our Panagia only committed the sin of Adam in her lifetime, the sin that was cleansed before she became the laboratory of the God/man union and which indirectly confesses her human nature, needed not only to unite the divine nature of Christ to his human one (without confusion, without change, without division and without separation) but also to ensure she is not elevated to the status of God,thereby destroying the belief in the One essence of God, like the Romeocatholics have done).
On the issue of Perpetual Virginity, please read also here.
Theotokos = from Theos (= God) and toketos (= child-birth). The one that gave birth to God
Theanthropos = from Theos = (God) and anthropos ( = man) = God/man..
only beloved = The KJV translation fails here to highlight that he is beloved and only-begotten (μονογενής), which is why the italiced term appears. The second translation from the Vulgate (a much better which is why I recommended this as the Bible to use in English) is much better for the word "only" is more accurate, being closer to "only-begotten" (monogenis in the Septuagint text), whereas the first translation changes the meaning totally.
according to the law = It is believed today that the so-called brothers of Jesus were in reality children of Joseph's with another woman; the law required that no woman giving birth to a child should be without a husband. God, as we know, did not come to destroy man's law but to "complete" it. Indeed, this is why Joseph was given to her as husband in the law (also, c.f. Matth. 1:18-20). Read also here.
above = it is actually around it in this case and not above(Greek: κύκλω= in a circle). A shortcoming of the translation.
Panagia = from pan- (= for all) and haghia (= female saint) . It means 'very' saint, the one more holy than all (angels and saints), the one above all the holy saints and the holy angels.