1. The action of the Holy Spirit points to the sovereign newness of the work that God is accomplishing.
2. The Spirit used Mary’s existing humanity so that Christ has our human nature.
3. The revelation of the virgin conception by the Spirit forbids any adoptionist Christology.
4. The work of the Spirit preserves both the reality of his union with us in genuine human nature and his freedom from the guilt and curse of Adam’s fall (Rom. 5:12-21) because his person is not of Adamic stock.
5. It underlines the principle that the work of the redemption engages every Person of the Trinity.
Sinclair Ferguson, The Holy Spirit
n.b. I jotted these down originally as class reading notes, so the wording may be any variation of quotation, paraphrase, and/or summary.