Who or what is the Holy Spirit?

Have you ever felt the presence of something — or someone — unseen, but deeply real? A peace that made no sense in the middle of chaos? A moment of insight or clarity that seemed to come from outside yourself?   

Christians call that the work of the Holy Spirit.

But who — or what — is the Holy Spirit?

Growing up, I found the idea quite confusing. I’d heard talk of the “Holy Ghost” and imagined a kind of divine Casper in a sheet. But the Holy Spirit is no Halloween figure. He is the third person of the Trinity — not a force or feeling, but a person. Invisible, yes. Mysterious, yes. But powerfully real.

From the very beginning of the Bible, we see the Spirit at work — "hovering over the waters" at creation (Genesis 1:2). In the Old Testament, the Spirit was given for specific tasks: to empower judges, prophets, and leaders. But with Jesus, everything changed.

When Jesus was baptised, the Spirit descended on him like a dove and remained (John 1:32). And before Jesus died, he made a promise to his followers: that the Father would send an Advocate — the Holy Spirit — to guide, comfort, and strengthen them (John 14:26).

That promise was fulfilled in dramatic style on the day of Pentecost. Picture it: a group of frightened disciples, locked away — when suddenly a violent wind fills the house, tongues of fire appear, and they begin to speak in other languages, declaring the wonders of God (Acts 2:1–4). It’s an extraordinary moment in history — but Pentecost is not just an event to remember. It’s a daily reality for anyone who follows Christ.

The word Jesus used for the Holy Spirit — parakletos — means “one who comes alongside.” A companion. A guide. A defender. A comforter. The Spirit whispers truth into our hearts, helps us make decisions, brings peace in times of fear, and reminds us who we truly are — beloved children of God.

Sometimes he acts powerfully — through healing, prophecy, even speaking in tongues. But often, his presence is quieter: a gentle nudge, a line of scripture that leaps off the page, a sense of calm that makes no logical sense.

I’ve known that calm — when I was told my cancer was advanced, and my prognosis was grim. In that moment, a deep peace settled over me, one I can only explain as supernatural. Others have told me of similar experiences: peace in grief, strength in fear, clarity in confusion. That’s the Spirit, too.

The Spirit also empowers us to speak — not always on platforms or pulpits, but in everyday conversations, where a timely word or act of love can change someone’s life. God loves to work through ordinary people — just look at Peter, the fearful fisherman who, filled with the Spirit, addressed a crowd and saw 3,000 people come to faith that day (Acts 2:14–41).

So how do we receive more of the Holy Spirit?

We ask.

The Church’s ancient prayer is still as powerful today: Come, Holy Spirit, come.

If you’ve never prayed that before, maybe now’s the time to try.

And then — simply wait. Be still. And let the mystery unfold..

Kate Nicholas is an award-winning author and speaker. Find out more about her books and events at www.katenicholas.co.uk