One of the difficulties we need to overcome when it comes to contemplating the Holy Spirit is to remove from our minds the consideration that the Holy Spirit is just some kind of impersonal force, kind of like what we hear about in "Star Wars." We need to resist the urge of hearing St. Paul’s words, like the lines in the movie, "May the force be with," and perhaps to resist the urge to says "And also with you."
A second difficulty might even come from some of the biblical images of the Holy Spirit: the dove, fire, wind or cloud. The images can help us understand the Holy Spirit, in some limited sense, but we must be careful not to identify the Holy Spirit with these impersonal images. The Holy Spirit is not a bird or a tongue of fire or a gentle or loud wind and certainly not a cumulo-nimbus cloud.
The Holy Spirit is one of the three divine persons of the Trinity. The Holy Spirit is "the Lord, the giver of life, who proceeds from the Father and the Son. With the Father and the Son he is worshiped and glorified," as we profess belief in every Sunday. We do not worship a bird, fire, wind or clouds; we worship God when we worship the Holy Spirit.
St. Paul helps us to understand this. A person, not an impersonal force, searches all things (1 Corinthians 2:10), knows the mind of God the Father (1 Corinthians 2:11), teaches the content of the Gospel to believers (1 Corinthians 2:13), dwells within believers (1 Corinthians 3:16; Romans 8:11; 2 Timothy 1:14), accomplishes all things (1 Corinthians 12:11), gives life to those who believe (2 Corinthians 3:6), cries out from within our hearts (Galatians 4:6), leads us in the ways of God (Galatians 5:18; Romans 8:14), bears witness with our own spirits (Romans 8:16), has desires that are in opposition to the flesh (Galatians 5:17), helps us in our weakness (Romans 8:26), intercedes on our behalf (Romans 8:26-27), works all things together for our ultimate good (Romans 8:28), strengthens believers (Ephesians 3:16), and is grieved by our sinfulness (Galatians 5:22-23).
We can understand the Holy Spirit as a divine person from the quote we started with: "The grace of the Lord Jesus Christ and the love of God and the fellowship of the Holy Spirit be with you all." We know that the Holy Spirit is not an "it," but a person, a "who."
St. Paul prays that we have fellowship with the Holy Spirit. The Greek word used here is "koinonia," which can also be translated "communion." We cannot have fellowship or communion with a force, a bird, wind, etc.