Christmas meant that Joseph learned that sometimes God surprises (1:20-21)
I doubt that many think of Joseph when, this Christmas, they give to their loved ones a “good surprise” at Christmas. We’ve all had our share of presents that were both surprises and generally unwelcomed ones. The best presents, of course, are both surprises and “just what we wanted.” The joy of it all rolls out in Dickens’ A Christmas Carol.
But, perhaps the biggest surprise of them all – both surprising and generally unwelcomed, was the news Joseph got: your girlfriend is pregnant, you are not the father, and you are to marry her, and in so doing you’ll lose your reputation as a tsadiq. But, this is what God wants for you, for Mary, and for the baby – and for the world. So hang on, this will be a wild ride for about 35 years. Imagine that as the gift under your tree!

The surprise, of course, which no one will receive as true, is that Mary is pregnant from the Holy Spirit – I call this the Big Fat Jewish Miracle Wedding Story. Mary knew it was true; Elizabeth, too. Joseph simply didn’t buy it – and it took some angelic manifestation for him to be convinced.
I imagine this conversation with Joseph and the angel:
A: God has sent me to tell you to marry Mary anyway.
J: No way.
A: Yes way.
J: No way.
A: Why not?
J: God says not to. I’m obedient.
A: God told me to tell you to disregard what you know and marry her anyway.
J: No way.
A: Why?
J: God says this in the Bible.
A: Times are changing, Joseph. I suggest you marry her.
J: OK. (But, tell God this is strange.)
A: He knows, I’m sure.
There is some deep irony here: Joseph thinks Mary (or someone else) has sinned; he chooses to divorce her so as not to sin; and God says that this baby, this little mamzer (Hebrew for an illegitimate child), will “save his people from their sins.”
Talk about irony: the one who others thought was born in sin will now be a sin-ending Savior.