Genesis 18:14 - "Is anything too difficult for the Lord?  At the appointed time I will return to you, at this time next year, and Sarah shall have a son."

God could have just as easily said this to Mary as He did to Sarah and Abraham.  The truth is, God seems to be in the habit of miraculous work.  The entire Bible foreshadows the work of God in Jesus Christ.

Is anything too difficult for God?  How has God asked this question of you?
What should Sarah's response be to God's promise?
How does joy help us wait for God's appointed time?