This study portrays Cyril of Alexandria as exegete and theologian through an examination of his Commentary on the Gospel John. It begins with an attempt to place Cyril and his commentary within their context. This work argues that Cyril wrote his Commentary on the Gospel of John early in his writing career, almost a decade before becoming bishop. Cyril’s commentary on the Johannine Gospel reveals his exegetical method and his strong Trinitarian theology. The commentary also focuses on the nature and work of the Holy Spirit: the indwelling of the Spirit is the beginning of the newness of life.