The will, or the soul's faculty of choosing good or evil, is an essential concept in Christian theology. Julian speaks of two wills in the human soul—a lower or “animal” one, and a “higher” or spiritual one. According to Julian, in the elect, the higher will predominates and is incapable of truly consenting to sin, so closely is its union with God. Julian's discussion of the will serves her larger discussion of the nature and faculties of the soul and how they relate to God.

Julian describes sin as “the sharpest scourge that any chosen soul can be struck with” (95). Yet, following the model of St. Augustine, Julian considers sin to have no positive reality in itself but to be a privation or negation of the good.

Julian also uses such words as falling or failing to describe sin. In the parable of the lord and the servant, in Chapter 51, the image of a servant stumbling and falling into a slough serves to represent sin. Julian emphasizes that God continues to love human beings despite their sins and that Christ out of love suffered to redeem man from sin.