The God to whom we pray is Spirit, and to worship Him, i.e., those who pray to Him must do so in spirit and in truth. This is impossible to accomplish left to ourselves. For, we are born of flesh and blood, and stained by sin, which separates us from God.
On our own, we do not know, nor can we understand the ways of the spirit. That is why God sent his Spirit to abide with us. God’s spirit enters our lives to lead us to the truth–the throne of God; for, God is spirit, and we must pray to Him in spirit.