The Holy Spirit, aka Holy Ghost, is the third person of the Trinity but is generally the least known and appreciated. In calling him the Paraclete or Advocate. Jesus hints at what the Spirit does and why he is so important....
Didymus the Blind shows how the spiritual fire and living water of the Holy Spirit give us new birth and transform us into new men and women, sharers in the divine glory and co-heirs with Christ....
Gregory of Nyssa here identifies the glory that Jesus speaks about in the Last Supper discourse of the Gospel of John with the Holy Spirit, the source of Christian unity. He also sees a reference to the Holy Spirit in the Song of Songs...
It's not just about being saved -- it's about taking others with us. Sharing the Good News of Jesus Christ is called evangelism or evangelization, and to share in this apostolic mission is a responsibility of all Christians....