Luke 1:29 and 38

But she was greatly perplexed at what he said, and kept carefully considering what kind of greeting this was. Then Mary said, “Behold, I am the servant of the Lord; may it be done to me according to your word.” And the angel left her.

Mary listened to the angel, perplexed at what he spoke, but she didn’t doubt his words. When she did speak, it was with confirmation in the trust of God and obedience to His word. Trust and obedience to the word of God will move mountains. Faith believes and acts on the word of God