Jesus was going to Galilee and on his journey he meets a Samaritan woman and the woman says: "Lord I see that you are a prophet" and then she asks him where to worship God if on the Mount Garizim in Samaria, or in Jerusalem, then Jesus answers her : "You worship what you do not know", Jesus responds that to the woman because  is talking to a person who "lives according to the flesh", the natural man does not know the spirit (1 Corinthians 2:14), then Jesus continues and He says:

God is spirit,
and those who
worship him must
woship him in spirit
and truth.
John 4:24

To say that God is spirit is to say that God is perfect and wise. God is the wisdom itself and God loves those who lives with wisdom (Book of Wisdom 7:28). Worship God in spirit is to adore him in Wisdom, for that reason Jesus says to the sinner woman: "you worship what you do not know".
We live according to the flesh or we live according to the spirit, for the natural or material man to live according to the spirit it's madness.
The ways of living are ways of perceive the reality, worshiping God in spirit means to contemplate God, to perceive him through the spiritual gift of knowledge, to contemplate his divine attributes.
In the Gospel of John, Jesus teach: This is the eternal life that they may know you the only true God, John 17:3.
Worship God means: "be renewed in the spirit of your minds, and put on the new man", Ephesians 4:23-24. This is to understand what is the progressive thinking, the faculties of the human mind are divided into two groups: the faculties of the soul which are imagination and fantasy and the faculties of the spirit which are intuition, inspiration and creativity.
When the faculties of the soul predominate in the mind we have the magical thought, when the faculties of the spirit predominate we have the progressive thinking. The new man is the progressive man.
The parables taught by Jesus usually make allusion to living beings this is so because life and spiritual gifts have the progressivity in common. To receive gifts we have to be progressive. Spiritual gifts are perfections.
Worshiping God means to understand the progressiveness of creation and the meaning of life: increase the spiritual gifts, increase the perfections of the universe.