God created Mary without the stain of original sin. There’s a great word called concupiscence, that means our tendency to sin caused by the Fall of Adam and Eve. Because of their sin, we are saddled with things like selfishness, pride, etc. Those things about which we say, “I’m just human.” Jesus was human, too, with free will and all the human emotions, but not the “human” weakness of concupiscence. Think of the scene in the garden: He felt fear, He wanted to turn away from the pain of the crucifixion, but He turned His will toward God and united His human will with God’s divine one. Mary has similar graces, but not the same. She was not God or a god. However, she was born without the concupiscence of original sin.

She could have said, “No thanks,” to the angel. Perhaps other women did; that’s something we’ll never know this side of Heaven. Just as Adam and Eve were 100% with God and THEY still figured out how to use their darn free will to turn from Him, Mary could have gone either way. This is where the explanation gets tricky: Mary could have sinned during her life, but she didn’t. She was given extra graces to preserve her from the stain of sin that would make her body unclean for the Christ Child. But yes, there is a fine line between receiving grace to HELP her make the right choices and a FORCING of right choices, aka no free will. Many people have grappled with this before us, and I’m sure there are some amazing answers for you in Catholic teaching. I double-checked the “without sin” teaching here: http://www.newadvent.org/cathen/15464b.htm

Here’s my best analogy as I try to explain what I truly believe by leap of faith (because sometimes that’s what it comes down to at the end): The Lord may protect you from a fatal car crash by a small twist of action, such as being slightly more alert as you enter an intersection or slowing down for no reason and narrowly avoiding a car crossing the center line on the highway. If you could “see” into the spiritual realm with such an incident, most people wouldn’t say God took away a person’s free will; they would simply praise Him for His protection. Mary was protected from some temptations and given graces to strengthen her; she was preserved from the weakness of concupiscence that everyone except Adam and Eve have been cursed with. But in the end, each choice was hers for the making. She just had a “better hand of cards” than the rest of us who aren’t chosen to be the Mother of God have been dealt. And I’m okay with that, myself. I’ve no ambition to see my Son die on a Cross, you know?

I hope that helps clear things up just a little. I feel like it was a bit rambling, but maybe the Holy Spirit infused some truth in it all! (If I pray for the Lord to help me, I’m offering up some of my free will, too, which I would gladly do to unite it with His own perfect will. Just another piece to the free will puzzle.)

Many Advent blessings to you!
Katie