'Spirit of God' in the Bible

For who among men knows the thoughts of a man except the man's spirit which is in him? Even so no one knows the thoughts of God except the Spirit of God.

But the natural man does not accept the things of the Spirit of God, for they are foolishness to him; and he cannot understand them, because they are spiritually discerned.

But in my judgment she is happier if she remains as she is; and I think that I also have the Spirit of God.

Therefore I tell you that no one who is speaking by the Spirit of God says, "Jesus be cursed," and no one can say, "Jesus is Lord," except by the Holy Spirit.