Yo. We need to talk about something.
There is no Mary.
Obviously there is no Mary in a nativity scene which involves a gay couple to parent Jesus, but the simple fact of Mary's absence here betrays a serious misunderstanding of the redemption we have in Christ. The natural question one is inclined to pose, if one has the time to comment on someone's obviously in-good-fun yard display (which I always have time for, because I am pretentious) is: Where did Baby Jesus come from? He couldn't have come from two Josephs. That doesn't make sense. And the obvious knee-jerk response to this question is "Oh! But where did he come from in the original story? Women can't conceive babies on their own! A virgin birth is nonsensical!"
Okay, that's fair, and true, and I'll not try to argue it. Because it's the freaking point.
Mary's conception of Christ by the Holy Spirit assisted by -- truly, enabled by -- her willing cooperation in the redemption of the entire human race is kind of where this whole Christianity thing starts. Listen, God spent the entire first half of salvation history sending messengers. He sent angels, he sent prophets, he sent clouds of fire and giant hungry fish. But the glory and beauty of Christmas is that, in Christ, he has given us all he has. He's given us his Son, and his Son in turn gives us his entire self, so much so that he becomes one of us. This occurs in the womb of Mary, after an angel receives her blessing permitting it to occur. Mary is the reason we freaking have Christmas in the first place.
Without Mary, there is no God-man.
Without Mary, there is no stable in Bethlehem.
Without Mary, there is no angel chorus flooding the sky to alert poor shepherds that their salvation has come.
Without Mary, there is no nativity scene.
Without Mary, there is no nativity.
The significance of Christmas is that Christ was born. Not sprung from the ground, not tossed from the sky, but born of a woman. For nine glorious months Jesus moved and grew and took nourishment from a woman, a woman who risked her actual life to bring him into the world. And Joseph is great, but he isn't Christ's mother. Joseph did not agree to give his own body over to the redemption of humanity. Joseph did not risk being stoned to death by growing his midsection. Joseph did not feel the pangs of labor as the God of history moved from the safety of his love out into the world that would kill him. Joseph did not give his body, again, to feed a newborn God of ages. And Joseph could not have ever accomplished any of these things -- not even with the help of another Joseph.
Erasing Mary from the story of Christmas is erasing Christmas. Not to mention, erasing a woman's contribution to the salvation of the whole of humanity is kind of, like, mildly sexist, dudes.
Two Josephs could not have done what Mary did. We at the very least owe her the respect of allowing her to appear in a depiction of the birth of her Son.