I was listening to Pastor Todd Wilken's Issues Etc. interviewing Dr. Lamb of Lutherans for Life. Dr. Lamb said something that struck me. David, inspired by the Holy Spirit, says in Psalm 51:5:
Surely I was sinful at birth,
sinful from the time my mother conceived me.
Dr. Lamb said that Jesus didn't begin as a baby in the manger; he began as a zygote. He began as a one-celled human being in Mary because that is where our sinfulness begins. Jesus' redemptive process had to begin at that point.
I never thought about it like that before.