Luke 1:35 says, "And the angel answered and said to her, The Holy Spirit will come upon you, and the power of the Most High will overshadow you; therefore also the holy thing which is born will be called the Son of God." The holy thing born of Mary was called the Son of God. The holy thing mentioned in this verse is God Himself, that is, Christ as the embodiment of God. He was born of God, possessing God's life and nature through the dispensing of the Holy Spirit. Although Christ was born of Mary (Matt. 1:16), He was a child of the Holy Spirit. The birth of Christ was directly of the Holy Spirit (v. 20). His source was the Holy Spirit, and His element was divine.
Some have the thought that conception cannot be considered a birth. But Matthew 1:20 clearly says that what was begotten in Mary was of the Holy Spirit. From the first day of Mary's conception, God was born in her. God was begotten into Mary by the dispensing of His nature by His Spirit.
First, God was born into Mary through His Spirit; then after the conception was completed, He, with the human nature, was born to be a God-man, possessing both divinity and humanity. This God-man is Jesus, our model.