The Johannine understanding of spirit and truth is not to be identified with the Gnostic usage of such terms. The Gnostic perspective is that of a secret godhead that is hidden from all except those who possess the special key of gnosis (knowledge). The stress in John is not on the hiddenness of God revealed through an alien messenger from without. Such a messenger in Gnosticism does not actually participate in human flesh because flesh is regarded as the creation of an evil sub god. Such a messenger always remains a spiritual reality even though it might employ the vehicle of flesh to awaken the elite Gnostics from the sleep of forgetfulness.179 But such a view is hardly the Johannine perspective on Jesus, the incarnate Son of God.
Borchert, Gerald L. John 1–11. Vol. 25A. Nashville: Broadman & Holman Publishers, 1996. Print. The New American Commentary.