The story is hardly credible to our modern minds. A fifteen-year-old girl informs her parents—I am assuming her parents were still living, though there is no mention of them—that an angel has visited her and now she is pregnant with the long-awaited Messiah.
We don’t expect the birth of Messiah, and few people know the Scriptures as Jewish people did then. Still, I suspect her family raised their eyebrows when Mary told them of the angel visit and her miraculous conception.
So she went to visit her cousin Elizabeth, no doubt accompanied by a family member for security; it was a long walk from Nazareth to Hebron. Mary was of the tribe of Judah and Elizabeth of the tribe of Levi; the relationship must have been through their mothers.
hen she arrived at the home of Elizabeth, she found things just as Gabriel had told her.
Elizabeth greeted her by saying (and the Bible says she greeted her in a loud voice) “Blessed art thou among women, and blessed is the fruit of thy womb. And whence is this to me, that the mother of my Lord should come to me?” An astounding greeting from an elderly lady to her very young cousin.
Elizabeth’s welcome surely eased any doubts Mary may have had about the reality of the divine event happening to her. Her response, “My soul doth magnify the Lord . . . ,” reveals a deep grasp of the Scriptures and shows that she knew how this event fit into the past, present and future of Israel and the world.
Again, from the perspective of our day we can hardly grasp that a fifteen-year-old girl could have such a depth of understanding. But Mary did, and she probably was not all that unique in her day.
But God not chose her on account of her knowledge. Why was Gabriel sent to Mary, out of the many young ladies of the Davidic line who must have been living? Mary’s simple response to the message of Gabriel reveals the answer: “Behold the handmaid of the Lord; be it unto me according to thy word.”
The words of Elizabeth underline the power of the simple faith and trust of Mary: “Blessed is she that believed: for there shall be a performance of those things which were told her from the Lord.”
Luke tells us more about Mary than any other New Testament writer. He must have known her and listened to her tell her story, from start to finish. She trusted, always watching to see what God would do next. She experienced a sorrow greater than any mother has ever known, yet still she trusted. She was there with the little group of believers at the beginning of the book of Acts. No doubt she experienced the outpouring of the Holy Spirit on the day of Pentecost and witnessed the glorious beginning of the church.
There is nothing that Mary can do for us today. But we can acknowledge her blessedness and follow her example of faith, trust and obedience.
Flatlander Faith 
In Eastern Orthodox teaching, Mary is the daughter of Joachim and Anna, an elderly couple who entrust her to the Temple at age three and leave her orphaned at age ten.
Their concept of Mary as the Theotokos, or Mother/Bearer of God, is much more nuanced than the Roman Catholic Virgin known in Western Christianity.
As for Joachim and Anna, we are given grandparents for Jesus.
I am curious about your giving Mary the age of 15 during her pregnancy. I would have placed it even earlier.
There are writers on the internet who place Mary in her twenties, but their reasons are at odds with the customs of that time. According to the custom in Judea, Mary could have been betrothed as young as 12-14 and would have been a spinster if she was 16 or older and still unmarried. That would have merited a mention by the gospel writer. I thought 15 was a fairly safe guess.
And would Elizabeth be understood as ‘elderly’ in the way we think? She might have been in her early 30s.
(What a great post, as usual! Very many thanks – as your Catholic follower, I am heartened and encouraged (if that isn’t a tortology) by your wonfderful posts and have been for years. I read them all.)
I think she was more likely around 60. She could have been considered barren at 30, but “well stricken in years” indicates a more advanced age..