I'm quite fond of I HEARD THE BELLS ON CHRISTMAS DAY. Words by Longfellow and lovely singable melody by Calkin:

I heard the bells on Christmas day
Their old familiar carols play,
And wild and sweet the words repeat
Of peace on earth, good will to men.

And thought how, as the day had come,
The belfries of all Christendom
Had rolled along the unbroken song
Of peace on earth, good will to men.

Till ringing, singing on its way
The world revolved from night to day,
A voice, a chime, a chant sublime
Of peace on earth, good will to men.

And in despair I bowed my head
"There is no peace on earth," I said,
"For hate is strong and mocks the song
Of peace on earth, good will to men."

Then pealed the bells more loud and deep:
"God is not dead, nor doth He sleep;
The wrong shall fail, the right prevail
With peace on earth, good will to men."

It's not just a 'Christmas song' but also a bit of a prayer for peace, written by Longfellow during the War Between the States.