He is a Helper to believers:
John 14:26
"But the Helper, the Holy Spirit, whom the Father will send in my name, he will teach you all things and bring to your remembrance all that I have said to you."
He is the Spirit of truth:
John 14:16-17
"And I will ask the Father, and he will give you another Helper, to be with you forever, even the Spirit of truth, whom the world cannot receive, because it neither sees him nor knows him. You know him, for he dwells with you and will be in you."
He is God who dwells with and in believers:
Romans 5:5
"and hope does not put us to shame, because God's love has been poured into our hearts through the Holy Spirit who has been given to us."