In order to appreciate what Sacred Scripture has to say about the Virgin Mary, we need a basic understanding of typology. Typology is the study of persons, places, events and institutions in the Old Testament that foreshadow greater realities in the New Testament. – Heavy stuff, I know, but stay with me.
Now in case you think this is some weird Catholic invention, the Bible demonstrates an awareness and usage of typology. In Romans 5:14 St. Paul tells us that Adam was a type of the one who was to come—Christ.
Early Christians understood that the Old Testament was full of types that were fulfilled in the New Testament, thus St. Augustine wrote, “the Old Testament is the New concealed, but the New Testament is the Old revealed” (Catechizing of the Uninstructed 4:8).
Here are a few more examples of biblical typology:
1 Peter 3:18-22 – Noah’s ark is a type of baptism.
Colossians 2:11-12 – Circumcision is a type of baptism.
John 3:14 – Bronze serpent is a type of the Crucifixion of Christ.
1 Corinthians 5:7 – The Passover lamb is a type of the sacrifice of Christ.
With that in mind, let’s see, at least partly, why Christians since the time of the apostles have referred to the Virgin Mary as the Ark of the New Covenant. You ready? If not, click here.
What was contained within Ark of the Covenant? “A golden urn holding the manna, and Aaron’s rod that budded, and the tables of the covenant” (Hebrews 9:4).
What was contained within the womb of Mary? Not manna, but “The bread of life” (John 6:35). Not Aaron’s rod -a sign of priestly authority- but the “High Priest” himself (Hebrews 3:1). Not the stone tablets containing the word of God but “the Word [who] was God (John 1:1).
So much could be said here but I don’t have the time and you probably don’t have the attention span. Let me ask you to grab your Bible – yes, I know, I know. An audacious request from a blogger – but do it! Compare the following verses of Scripture.
2 Samuel 6:1-11 – Luke 1:39.
Old Testament – The ark traveled to the house of Obed-edom in the hill country of Judea. New Testament – Mary traveled to the house of Elizabeth and Zechariah in the hill country of Judea.
2 Samuel 6:14 – Luke 1:41
OT – Dressed as a priest, David danced and leapt in front of the ark. NT – John the Baptist – of priestly lineage – leapt in his mother’s womb at the approach of Mary.
2 Samuel 6:9 – Luke 1:43
OT – David asks, “How can the ark of the Lord come to me?” NT – Elizabeth asks, “Why is this granted me, that the mother of my Lord should come to me?”
2 Samuel 6:15 – Luke 1:42
OT David shouts in the presence of the ark. NT Elizabeth “exclaimed with a loud cry” in the presence of the Mary.
2 Samuel 6:11 – Luke 1:56
OT – The ark remained in the house of Obed-edom for three months. NT – Mary remained in the house of Elizabeth for three months.
2 Samuel 6:11 – Luke 1:39-42
OT – The house of Obed-edom was blessed by the presence of the ark. NT – The word blessed is used three times; surely the house was blessed by God.
2 Samuel 6:12, 1 Kings 8:9-11 – Luke 1:56, Luke 2:21-22
OT – The ark returns to its home and ends up in Jerusalem, where God’s presence and glory is revealed in the temple. NT – Mary returns home and eventually ends up in Jerusalem, where she presents God incarnate in the temple.
Obviously much more could be said, but are you beginning to see why Christians refer to the Virgin Mary as the Ark of the New Covenant? Read what Athanasius of Alexandria (c. 296–373) had to say about her
“O noble Virgin, truly you are greater than any other greatness. For who is your equal in greatness, O dwelling place of God the Word? To whom among all creatures shall I compare you, O Virgin? You are greater than them all O [Ark of the] Covenant, clothed with purity instead of gold! You are the ark in which is found the golden vessel containing the true manna, that is, the flesh in which divinity resides” (Homily of the Papyrus of Turin).
 This commentary was taken from Catholic apologist Steve Ray.