Complex sentence: The main feat of Esoteric Christianity is to learn the mysteries of God, (see Raziel), and rise to higher consciousness and theurgy is, in the esoteric tradition, using this knowledge to heighten one's own spiritual nature.
Split into simpler sentences: The main feat of Esoteric Christianity is to learn the mysteries of God (see Raziel) and to rise to higher consciousness. Theurgy, in the esoteric tradition, using this knowledge to heighten one's own spiritual nature.