In the beginning

Question: 

Which book of the Bible opens with the words, "In the beginning was the Word..."

Illuminated manuscript of the first page of John's Prologue
Answer: 

The Gospel of John.  That other beginning you may have thought of is in Genesis 1:1 and John is making a connection that would have been obvious to his readers.

John 1:1-18 is known as John's Prologue and is the only form of the Christmas story we get in John's Gospel.

Above is an illuminated manuscript, showing the beginning of John's prologue in Latin.