When Jesus was discussing His departure with His disciples he made a promise to them. It’s a promise to us as well. First He said in John 14:1, “Let not your heart be troubled…” Then in John 14:16 He told them that the Father 
would send someone to them who would fill the void of His absence. He would petition the Father and the Father would “give you another Helper, who will abide with you forever.”
The preciousness of this promise comes home as we understand the meaning of the Greek word translated “another.” In Greek there are two words that are translated as “another.” One of those words is “heteros.” It means another of a different kind. If I had a pen that didn’t write, I’d ask for “another” pen of a different kind. I would want one that worked as opposed to one that didn’t work. When heteros is used it always refers to another of a different kind. The other word is “allos.” It means another of the same kind. If I had a pen that really worked well and I asked for “another” one, I’d want one of the same kind. As Jack Hayford observes, “Jesus’ use of allos for sending another Comforter equals ‘one besides Me and in addition to Me but one just like Me. He will do in My absence what I would do if I were physically present with you.’ The Spirit’s coming assures continuity with what Jesus did and taught. ‘Continuity of what Jesus did and taught!’ No wonder Luke presents Acts as a continuation through Holy Spirit fullness ‘of all that Jesus began both to do and teach’ (1:1).”
The three persons of the God head; Father, Son and Holy Spirit, are of the very same essence. They are of the same kind. All three are consistent in all they do and all they say. Jesus said he speaks only what the Father tells Him. The Holy Spirit does nothing outside the will of the Father and the Son. It is the essential oneness, likeness, that retains the idea of “one” God, yet revealed to us in three persons. When Paul closes his second letter to the Corinthians he does so with a blessing from this consistent, triune God. He says, “The grace of the Lord Jesus Christ and the love of God and the fellowship of the Holy Spirit be with you all” (2 Corinthians 13:14).