"Truly He taught us to love one another;
His law is love and His gospel is peace.
Chains shall He break for the slave is our brother;
And in His name all oppression shall cease."
Those are some pretty powerful lyrics. More, these were political and prophetic lyrics.
Recall that the song and the French poem were written in 1847. The English version was written in 1855, six years before the American Civil War and eight years before the Emancipation Proclamation. O Holy Night, it turns out, was a song of political resistance and protest.
-- Richard Beck, Christmas Carols as Resistance Literature