God is Spirit, and those who worship Him must worship in spirit and truth. - John 4:24, NKJV
To worship God means to attribute worth to God through obedience to God, preoccupation with God, and praise of God. The Samaritan woman at the well in Sychar said, in essence, “Oh, well, I worship God.” And Jesus corrected her, “You Samaritans worship what you do not know.” Why was her worship invalid? Because she was substituting the traditions and rituals of her religion for a personal relationship with God through faith. So Jesus explained, “God is spirit, and His worshipers must worship in spirit and in truth” (John 4:24, NIV).
What does it mean to worship “in spirit and in truth”? To worship God in spirit means to worship Him in deepest sincerity from the heart as one who is indwelled by the Spirit of God. To worship Him in truth means to worship Him honestly, without hypocrisy, through faith in His Word, both the Living Word, which is Jesus, and the written Word, which is the Bible.
From God's Story