The Holy Spirit is revealed in scripture to be the third person in the eternal Godhead. It is a title that is often associated with the Father and the Son.
After believing and trusting in the Lord Jesus Christ we are sealed with the Holy Spirit of promise, Who is the of our inheritance until our complete redemption.
Ephesians 1:13-14 In Him you also trusted, after you heard the word of truth, the gospel of your salvation; in whom also, having believed, you were sealed with the Holy Spirit of promise, 14 who is the guarantee of our inheritance until the redemption of the purchased possession, to the praise of His glory.
Everything that has been committed to us from Jesus Christ and the Father are kept in our lives because of the work of the Holy Spirit in our lives.
2 Timothy 1:13-14 Hold fast the pattern of sound words which you have heard from me, in faith and love which are in Christ Jesus. 14 That good thing which was committed to you, keep by the Holy Spirit who dwells in us.
Jesus said that the Holy Spirit would represent Him in every way. He came to came to take Jesus' place and in so doing He fulfills the ministry of Jesus on the earth. In order to do this He must be equal to Jesus; and He must be a person. The Holy Spirit is the silent member of the eternal Godhead. By that we mean He never projects Himself He always glorifies God the Father and God the Son.
If one experience of being born again and becoming a new creature were sufficient for all God's purposes then why did Jesus refrain from this ministry until He was endued with power from on High? It was because of His need for anointing which constituted power from on High. It was at the Jordan that He obtained perfect domination over the world, the flesh, and the devil, and this was fully proved in the wilderness.
Just as Jesus needed the fullness of the Holy Spirit to fulfill the purpose He had been sent forth to accomplish, so we need His ministry in our lives as well. The Holy Spirit has been given to us from the Father to bring us into the fullness of all that God desires for our lives. He searches the deep things that are in the Father's heart and reveals them unto us.