"And the angel answered her, 'The Holy Spirit will come upon you, and the power of the Most High will overshadow you; therefore the child to be born will be called holy—the Son of God.'" —Luke 1:35
I think we sometimes forget that the Lord Jesus was born into our world and not from it. He came to us, outside of earthly history. Jesus wasn't a man becoming God, but rather God Himself entered our sphere of existence in human form—as a newborn baby.
Yes, baby Jesus grew up to be tempted and betrayed, yet He did not succumb to sin. Nether outwardly or inwardly. Just think of that! This has baffled my mind since I was a young girl sitting in my father's church as he gave the "Christmas sermon" the sanctuary all bedecked with fluffy red and white pointsettias, and tall tapers flickering on the communion table. God came here—to us—to save the world!
So, when we're born into God's family (this is salvation, when we repent of doing things are own way and yield ourselves totally to His will), then Christ springs alive in us. When this happens, we, too, become one with the Lord. His spirit envelopes ours—Christ is formed in us. (Galatians 4:19: "My children, I am suffering birth pains for you again until Christ is formed in you.") We crave Christ's ways, His will. We look to Him in everything we do and say. We are so in love with Him, we want to live every minute, every day of the rest of our lives for Him alone.
A blessed Advent Season of Joy and Light and Truth!