The Holy Spirit is God. He is not an "it." He is not a divine influence. He is not a fleecy white cloud. He is not a ghost nor a concept. He is a person possessing a will, intellect and emotions. He is God - with all the attributes of deity. He is the third person of the Trinity - co-equal with God the Father and God the Son. There is only one God, but He manifests Himself in three persons, whom we call the Trinity.
I cannot define the Trinity. No one can. Dr. Wilbur Smith, one of my seminary professors, once shared in class, "The man who denies the Trinity will lose his soul. The man who tries to understand the Trinity will lose his mind." We, who are finite, cannot comprehend God, who is infinite.
We try to illustrate the concept of the Trinity, but the attempt is wholly inadequate. For example, I could say that a man has a body, a mind and a spirit - which one is the man? Or I could describe H20 as a liquid, a solid or a vapor, depending on whether it was water, ice or steam. Which one is H20? Or, a man is a husband, a father, and a son - yet, he is one man. No illustration is adequate. At best, it can only suggest what God is like.
As much as you and I would like to know all about the Trinity, some of our questions must wait until we are with our Lord in eternity. Then we will understand completely. In the meantime, consider what Paul says in Romans 11:
Oh, what a wonderful God we have! How great are his wisdom and knowledge and riches! How impossible it is for us to understand his decisions and his methods! For who among us can know the mind of the Lord ? Who knows enough to be his counselor and guide?
And who could ever offer to the Lord enough to induce him to act? For everything comes from God alone. Everything lives by his power, and everything is for his glory. To him be glory evermore."