And the Word became an embryo…
Christmas celebrates the birth of Jesus Christ, what is theologically called the Incarnation. God the Son, the Word, took on flesh and dwelt among humanity, being both fully God and fully Man (John 1:1-14). He did this to deal with our sin. The sole purpose of his birth was to grow up and die, thereby dealing with the darkness of sin us that separates us from the Light of Life (Matt. 1:21; Luke 2:11; 24:45-47; Isa. 9:2-6; 53:4-12; Jn. 1:9-13). Yet rarely have I stopped to consider the magnitude of the fact that Jesus did not appear on the scene as an adult or fully developed. As God, couldn’t He have passed over some of the steps in human growth? Instead, when the Word took on flesh, He did so like every other human being. He became a zygote, developed naturally as a blastocyst, embryo, and fetus. He spent 9 months in the womb of a virgin where his muscles, heart, brain, and organs developed and grew like the rest of us. He did not simply take on a postnatal identity; he took on a prenatal identity as well. He associated with us in all of our vulnerability, growth, and diversity.
The Word became an embryo and dwelt among us. By clothing himself in full humanity, the life of Christ from the womb to the post-grave gives us a blue print for how to treat others with dignity. If He was willing to identify with us at our most vulnerable and weak, what should that tell us about how we treat embryos and those who are weak among us today?
Because of sin, the Word took on the form of an embryo. He sympathized with us in our weakness because only His strength can save us. In a world that champions tolerance, his birth was the greatest act of both acceptance and intolerance. His holiness cannot tolerate sin and his love refuses to. He came as the Savior, and calls us to come to him for rest just as we are. Yet he does not leave us as we are, but rather offers to transform and develop us to live out our full humanity.
This Embryo, the Word, the Incarnation, is the reason to celebrate Christmas. It is the reason to celebrate life.
Penny of a Thought 
Are you speaking of original sin inherited by all of us or a nature designed by god to be sinful?
I fear you may have imported quite a few assumptions into this post – and then built on them. In truth, we don’t know anything about the Incarnate Word’s chromosomal constitution. Whilst we believe that He was fully man, we need to be wary of defining that in genetic/chromosomal terms. We know a young woman conceived, but it seems that semen wasn’t involved so we can’t really say anything about zygote, blastocyst, embryo. We know that she carried and then gave birth to her firstborn, but we aren’t told the length of gestation.
There is no doubt that Jesus identified with the weak and marginalised, and taught his followers to do the same (including feeding the hungry) but I think all of the above is a dubious basis upon which to build an argument that all zygotes/embryos are human beings, and where that then takes us. It is also clear that God has identified with those who are infertile.
For some further thoughts on this, have a look here:
http://t-rinder.typepad.com/blog/2013/02/what-makes-you-a-person.html