In Kabbalah, the sin of eating from the Tree of Knowledge brought the mixture of good and evil into the world. We now must separate the light (good) from the darkness (evil) inside each of us. Once the evil is separated from holiness through teshuvah, the Shechinah, or the Presence of God, can come back down to earth, where the sin of the Tree had caused Her to depart, as described in the Visions and Parables of Zenos. Knowing good from evil gives us true free agency, the wisdom from the Divine Feminine, the Light of Christ, to choose for ourselves.
See 1 Moses 4:16, 5; Melchizedek 3-9; Genesis 2:9, 3; Visions and Parables of Zenos; 2 Nephi 1:94-121 RAV, 2:14-27 OPV.