During Advent I've been working my way through John Piper's excellent
The Dawning of Indestructible Joy. One of my favourite bits so far has been this:
...the meaning of Christmas is that what is good and precious in your life need never be lost, and what is evil and undesirable in your life can be changed. The fears that the few good things that make you happy are slipping through your fingers, and the frustrations that the bad things you hate about yourself or you situation can't be changed - these fears and these frustrations are what Christmas came to destroy
It is God's message of hope this Advent that what is good need never be lost and what is bad can be changed. The Devil works to take the good and bring the bad. And Jesus came to destroy the works of the Devil.
John Piper, The Dawning of Indestructible Joy: Daily Readings for Advent, p.38.