What we have in the Christian doctrine of the Holy Spirit is Deity present among us. He is not God's messenger only, He is God. He is God in contact with His creatures, doing in them and among them a saving and renewing work.
The Persons of the Godhead never work separately. We dare not think of them in such a way as to "divide the substance." Every act of God is done by all three Persons. God is never anywhere present in one Person without the other two. He cannot divide Himself. Where the Spirit is, there also is the Father and the Son. "We will come unto him and make our abode with him." For the accomplishment of some specific work one Person may for the time be more prominent than the others are, but never is He alone. God is altogether present wherever He is present at all.