Summary: Mary teaches us that we too can be used by God to change the world. We learn from her that . . . Faith is not age-dependent. Faith positions us to be part of the greatest event in all human history. Faith means do what God says regardless of the cost.
The question arises, why did Mary anticipate having a baby before she had sexual relations? Why did she not simply assume that the angel meant she would have a baby after she and Joseph were married? It is doubtful she had Isaiah 7:14 (quickview)  in mind, in which God said a virgin would give birth to a son and call him Immanuel. But something in the tone of the angel’s message led her to understand that she would immediately fall pregnant, before she was married.
The angel answered Mary’s question by explaining that . . .
Mary Would Become Pregnant Through The Miracle-Working Power of The Holy Spirit
The Holy Spirit would come upon Mary and create the child within her womb. That is why the child will be the holy one who is called the Son of God.
The image of the Most High overshadowing Mary reminds us of the Spirit of God hovering over the waters of the deep at creation (Genesis 1:2 (quickview) ). We also recall the cloud of the glory of the lord that descended upon the Tabernacle (Exodus 40:34 (quickview) ,35).
Although Mary had not asked for a sign, the angel offered proof to Mary of God’s power by pointing out that . . .
Elizabeth’s Pregnancy Was Proof Of God’s Power
Gabriel told Mary that her relative Elizabeth’s pregnancy was proof that nothing is impossible with God. Elizabeth had never had children and she was past child-bearing age when the angel appeared to Zechariah and told him that Elizabeth would bear a son (Luke 1:19 (quickview) ).
The angel’s visit to Mary took place in the sixth month of the pregnancy of Mary’s cousin Elizabeth. The significance of this was that after Mary was visited by the angel she was able to visit Elizabeth and see another miracle – that a woman past child-bearing age was pregnant. While not as phenomenal a miracle as what took place in Mary, it nonetheless confirmed the angel’s message.
With quiet faith Mary accepted the angel’s explanation and submitted herself to the Lord.
Mary Obeyed The Lord
Lk 1:38 “I am the Lord’s servant,” Mary answered. “May it be to me as you have said.” Then the angel left her.
Knowing the enormous price she was about to pay, Mary surrendered herself first to the Lord and then to His plan. Notice that although we have made much of the cost to Mary, she says not a word of it!
She said, “I am the Lord’s servant.” There’s a wonderfully childlike aspect to her faith. With absolute trust Mary bows herself to the will of God and declares herself to be His servant. Her words must have brought great joy to the heart of God. He has always longed for His people to give themselves so unreservedly to Him.
Mary also surrendered herself to the Lord’s plan for her life, as costly as it was going to be: “May it be to me as you have said.”
Paul praised the Macedonian churches for following the same sequence when they gave sacrificially to help other Christians in need:
They gave themselves first to the Lord, then they gave their money. God wants us to first give Him ourselves and then give Him our obedience.