“Man’s true knowledge of God is the fruit of his deification effected by God. The further he advances on the road to deification, the fuller and surer is the knowledge of God that he gains. Communion in the sacraments, the keeping of the divine commandments, prayer, and particularly the mystical vision of uncreated light lead man not only to union with God but to knowledge of Him. This knowledge . . . is the gift conferred on those who live according to Christ and in the Holy Spirit” (Mantzaridis, G. I. . The deification of man, p. 113).
The above is what it means to worship God the Father in Spirit and in Truth, for as Jesus Christ said, “For the hour comes and now is, when the true adorers shall adore the Father in spirit and in truth. For the Father also seeks such to adore Him. God is a spirit: and they that adore Him must adore Him in spirit and in truth” (Jn 4:23-24).