That the Most Holy Virgin Mary must be venerated as the Theotokos (Mother of God) is seen from the following:
“Therefore the Lord Himself shall give you a sign: behold, the Virgin shall conceive and bear a Son, and you shall call His name Immanuel.” (Isaiah 7:14; cf. Matthew 1:23)
“And the angel answered and said unto her: The Holy Spirit shall come upon you, and the power of the Most High shall overshadow you; therefore the holy thing which is born shall be called the Son of God.” (Luke 1:35)
“And why is this granted me, that the mother of my Lord should come to me?” (Luke 1:43)
From the following Word of God we see that she remained a Virgin before the birth of the Son of God from her and at the birth itself:
“And the angel said unto her: Fear not, Mary, for you have found favor with God.” (Luke 1:30)
“And behold, you shall conceive in your womb and bring forth a Son, and shall call His name Jesus.” (Luke 1:31)
“He shall be great, and shall be called the Son of the Most High; and the Lord God shall give unto Him the throne of His father David.” (Luke 1:32)
“And He shall reign over the house of Jacob forever, and of His kingdom there shall be no end.” (Luke 1:33)
“Then said Mary unto the angel: How shall this be, seeing I know not a man?” (Luke 1:34; see verse 35)
“But while he thought on these things, behold, an angel of the Lord appeared unto him in a dream, saying: Joseph, son of David, fear not to take unto you Mary your wife, for that which is conceived in her is of the Holy Spirit.” (Matthew 1:20)
“Then Joseph, being raised from sleep, did as the angel of the Lord had bidden him, and took unto him his wife.” (Matthew 1:24)
“And knew her not till she had brought forth her firstborn Son; and he called His name Jesus.” (Matthew 1:25)
Remaining faithful to her vow of virginity (“I know not a man”), Mary remained a Virgin also after the Nativity, according to the prophecy:
“And the Lord said unto me: This gate shall be shut, it shall not be opened, and no man shall enter by it; because the Lord, the God of Israel, has entered by it; therefore it shall be shut.” (Ezekiel 44:2)
Explanation: Just as Jesus Christ called Himself the door by which one enters heaven (John 10:9), so the Virgin Mary is mystically called a gate by the prophet – the Gate through which the Savior came to earth, after which she remained “shut,” that is, by God’s decree she remained a Virgin forever.
The Virgin Mary herself told the angel that she knows not a man (Luke 1:34), and she said this while she was betrothed to Joseph:
“Now the birth of Jesus Christ was on this wise: When His mother Mary was betrothed to Joseph, before they came together, she was found with child of the Holy Spirit.” (Matthew 1:18)
Therefore, we must think of Joseph that he was called her husband not in the proper sense of a spouse, a fleshly cohabitant, but in the sense of a guardian husband.
Jesus Christ Himself calls the Virgin Mary “woman” not in the proper sense of wife; likewise, the angels call Mary Magdalene “woman” in the sense of denoting her sex, not her marital state:
“When Jesus therefore saw His mother, and the disciple standing by whom He loved, He said unto His mother: Woman, behold your son!” (John 19:26)
“Jesus said unto her: Woman, what have I to do with you? My hour has not yet come.” (John 2:4)
“The first day of the week comes Mary Magdalene early, when it was yet dark, unto the sepulcher, and sees the stone taken away from the sepulcher.” (John 20:1)
“And they (the angels) say unto her: Woman, why do you weep? She said unto them: Because they have taken away my Lord, and I know not where they have laid Him.” (John 20:13)
“Jesus said unto her: Woman, why do you weep? Whom do you seek? She, supposing Him to be the gardener, said unto Him: Sir, if you have borne Him away, tell me where you have laid Him, and I will take Him away.” (John 20:15)
From this it is evident that the “brothers” of Jesus Christ mentioned in the Gospel are not His blood brothers from His mother: they are either children of Cleopas and Mary, the sister of the Most Holy Theotokos, and thus cousins of the Savior; or they are children of Joseph from his first lawful marriage, not from Mary.
The Most Holy Virgin is called Lady, Queen of Heaven, because she is the Mother of the Lord and King of Heaven:
“Daughters of kings are among your honored women; the Queen stands at your right hand in gold of Ophir.” (Psalm 44:10; cf. John 19:26)
The Word of God also speaks of the spiritual greatness of the Virgin Mary:
“And my spirit has rejoiced in God my Savior.” (Luke 1:47)
“For He has looked upon the low estate of His handmaiden; for behold, from now on all generations shall call me blessed.” (Luke 1:48)
“For He that is mighty has done great things for me, and holy is His name.” (Luke 1:49)
Jesus Christ Himself was the first to set the example of venerating the Virgin Mary as the Mother of God:
“And He went down with them and came to Nazareth, and was subject unto them. And His mother kept all these sayings in her heart.” (Luke 2:51)
Explanation: Jesus Christ, during His earthly life, undoubtedly showed all honor to the Most Holy Virgin as His Mother; and even at the very moment of His death, He showed special filial care for her, entrusting her to the care of John the Theologian (John 19:26–27), and in his person He taught all others also to venerate the Most Holy Theotokos.
That the Ever-Virgin Mary was venerated even before the birth of the Savior is seen from the following:
“And it came to pass, that when Elizabeth heard the greeting of Mary, the babe leaped in her womb; and Elizabeth was filled with the Holy Spirit.” (Luke 1:41)
“And she spoke out with a loud voice and said: Blessed are you among women, and blessed is the fruit of your womb!” (Luke 1:42)
“And why is this granted me, that the mother of my Lord should come to me?” (Luke 1:43)
“And it came to pass, as He (Jesus Christ) spoke these things, a certain woman from the crowd lifted up her voice and said unto Him: Blessed is the womb that bore You, and the breasts which You have sucked!” (Luke 11:27)
“And the angel came in unto her and said: Hail, full of grace! The Lord is with you; blessed are you among women!” (Luke 1:28)
The prayerful invocation with the words: “Most Holy Theotokos, save us” and her intercession before God is explained, for example, by the following consideration:
The Apostle Paul was not the Savior, but said of himself:
“To the weak I became as weak, that I might gain the weak: I am made all things to all men, that I might by all means save some.” (1 Corinthians 9:22)
And to Timothy he wrote:
“Take heed unto yourself and unto the doctrine; continue in them: for in doing this you shall both save yourself, and them that hear you.” (1 Timothy 4:16)
If the apostles could save others – that is, help their salvation – how much more can the Mother of God do this? It is in this sense that we cry out to her:
Most Holy Theotokos, save us!
Missionary Guide to the Bible