Christianity believes the Holy Spirit or the Holy Ghost to be one of the three entities of the Holy Trinity making up one singular God, the rest two being God the Father and God the Son, i.e., Jesus Christ. The Spirit was the latest conceptualization out of all the three, the first two appearing much earlier in the scheme of the spiritual Christian mind. That is why there have been different interpretations as of the role it plays in the spiritual journey of the mankind on earth.
