Now the birth of Jesus Christ was on this wise: When as his mother Mary was espoused to Joseph, before they came together, she was found with child of the Holy Ghost.  Then Joseph her husband, being a just man, and not willing to make her a publick example, was minded to put her away privily.  But while he thought on these things, behold, the angel of the Lord appeared unto him in a dream, saying, Joseph, thou son of David, fear not to take unto thee Mary thy wife: for that which is conceived in her is of the Holy Ghost.  And she shall bring forth a son, and thou shalt call his name JESUS: for he shall save his people from their sins.

Matthew 1:18-21