The mystery of Christmas

We should be wary of separating form and content. The miracle of Christmas is that Jesus was "conceived by the Holy Spirit" and "born of the virgin Mary". This is the form. The content is the mystery of Christmas: the incarnation, "the unio hypostatica, the genuine unity of the true God and the true man in the one Jesus Christ."

These are the main ideas I got from re-reading the chapter, The Mystery and the Miracle of Christmas, in Dogmatics in Outline, by Karl Barth.