Holy Ghost/Spirit.
For the Christian God is more than one, he is three, father, son and Holy Ghost/Spirit. But it is only believers in the death and resurrection of Jesus who recieve the promised empowerment of this invisible man.
The New Testament tells us He is the comforter and He comes alongside believers to help us to serve, to pray to preach, to give our testimony.
The world cannot have Him, because they do not believe and are unrepentant?
John 11:25, 14:26, Acts 2:33, 2 Corinthians 12:10, Ephesians 6:18.
Ask me and I will tell you! 