Book 1 - Knowledge of God the Creator
Chapter 15 - Of Human Nature, the Soul, Image of God, Free Will
Sections 1-4 - Man's nature deformed; yet his soul bears, though almost obliterated, the image of God
Section 4 - Discern the true nature of God's image from its renewal through Christ
Since our image was ruined in the Fall, we can only tell what it is supposed to be by our restoration in Christ. 1 Cor 15:45; Col 3:10; Eph 4:24. Believers continue to reflect God's image, and it will be complete when we see Him face to face (2 Cor 3:18).
Section 5 - Manichaean error of the soul's emanation
Servetus brings back this error, that our soul is of God's essence.
This would make God inconstant, like man's soul obviously is.
Gen 2:7; Acts 17:28; Ecc 12:7.