Question: "Why is the Virgin Birth so important?"
Answer: The doctrine of the virgin birth is crucially important (Isaiah 7:14; Matthew 1:23; Luke 1:27, 34). First, let’s look at how Scripture describes the event. In response to Mary’s question, “How will this be?” (Luke 1:34), Gabriel says, “The Holy Spirit will come upon you, and the power of the Most High will overshadow you” (Luke 1:35). The angel encourages Joseph to not fear marrying Mary with these words: “What is conceived in her is from the Holy Spirit” (Matthew 1:20). Matthew states that the virgin “was found to be with child through the Holy Spirit” (Matthew 1:18). Galatians 4:4 also teaches the Virgin Birth: “God sent His Son, born of a woman.”
From these passages, it is certainly clear that Jesus’ birth was the result of the Holy Spirit working within Mary’s body. The immaterial (the Spirit) and the material (Mary’s womb) were both involved. Mary, of course, could not impregnate herself, and in that sense she was simply a “vessel.” Only God could perform the miracle of the Incarnation.
However, denying a physical connection between Mary and Jesus would imply that Jesus was not truly human. Scripture teaches that Jesus was fully human, with a physical body like ours. This He received from Mary. At the same time, Jesus was fully God, with an eternal, sinless nature (John 1:14; 1 Timothy 3:16; Hebrews 2:14-17.)
Jesus was not born in sin; that is, He had no sin nature (Hebrews 7:26). It would seem that the sin nature is passed down from generation to generation through the father (Romans 5:12, 17, 19). The Virgin Birth circumvented the transmission of the sin nature and allowed the eternal God to become a perfect man.