What does it mean to be "Holy"?

Have you ever watched a child try to clean a window? She sprays the glass, wipes it with a paper towel, steps back proudly, and then the sunlight shifts and reveals a dozen streaks she never saw. So she sprays again, wipes again, and this time catches most of them. But later in the afternoon, when the light comes from a different angle, new smudges appear. The glass looked clean in one light. It did not look clean in another.

We have a similar problem with the word “holy.” We use it constantly. We sing it in hymns. We hear it in prayers. We attach it to books, to water, to days on the calendar. But if someone stopped us mid-sentence and asked, “What exactly do you mean by that word?” most of us would hesitate. We might say something about moral goodness or religious devotion. We might gesture vaguely toward the idea of being “set apart.” And we would not be wrong, but we would sense, even as we spoke, that we had not said enough.

Like the streaks on the window, there is always more to see when the light shifts.

So what does it really mean to say that God is holy? And what does it mean that we are called to be holy ourselves?

 

The Blazing Otherness

The Hebrew word most often translated “holy” is qadosh, and its root meaning points toward separation, distinction, otherness.

When the seraphim cry out in Isaiah’s vision, “Holy, holy, holy is the LORD of hosts; the whole earth is full of his glory” (Isaiah 6:3, NRSV), they are not simply saying that God is morally pure, though He is. They are declaring something far more staggering: that God is utterly unlike anything else that exists.

He is not a bigger version of us. He is not the highest rung on a ladder we can climb. He is, in His very being, beyond every category we possess. He is being itself.

This is why Isaiah’s immediate response is not worship in any comfortable sense. It is terror. “Woe is me! I am lost, for I am a man of unclean lips, and I live among a people of unclean lips; yet my eyes have seen the King, the LORD of hosts!” (Isaiah 6:5).

The holiness of God did not make Isaiah feel inspired. It made him feel undone.

He suddenly saw himself the way the afternoon sunlight reveals the streaks on glass. Everything he thought was clean enough turned out not to be.

This is the first and most important thing we must understand about holiness: it begins with God, not with us.

Holiness is not primarily a moral achievement. It is an attribute of the divine nature. God does not conform to some external standard called “holiness.” He is the standard. His holiness is the white-hot center of His being, the blazing purity and completeness from which all other perfections flow.

 

Purity and Firmness

St. Thomas Aquinas taught that holiness signifies two things: purity and firmness.

Purity, because what is holy is free from the stain and corruption of sin. Firmness, because what is holy is established, stable, and unwavering in its orientation toward God.

These two dimensions deserve careful attention, because they correct two common misunderstandings.

The first misunderstanding is that holiness is merely about avoiding bad things.

Purity, in the deepest sense, is not just the absence of contamination. It is the presence of undivided wholeness. Think of the difference between an empty room and a room filled with light. Both might be called “clean,” but only one is radiant. Biblical purity is not the emptiness of a life scrubbed free of obvious sin but left purposeless. It is the radiance of a life so filled with God that there is simply no room for what is contrary to Him. “Blessed are the pure in heart,” Jesus says, “for they will see God” (Matthew 5:8). The pure heart is not merely the heart that has stopped sinning. It is the heart that has become so singularly focused on God that it can perceive Him.

The second misunderstanding is that holiness is fragile, something that must be protected in a glass case, kept away from the rough edges of ordinary life.

But Aquinas says holiness involves firmness. The holy person is not brittle. She is anchored. Her life has a stability that comes not from avoiding difficulty but from being rooted in something that does not change. The Psalmist captures this beautifully: “Those who trust in the LORD are like Mount Zion, which cannot be moved, but abides forever” (Psalm 125:1).

Firmness is not rigidity. It is the deep, living steadiness of a tree whose roots have found water.

Put these two together, purity and firmness, and you get a picture of holiness that is both luminous and strong. The holy person is someone whose inner life has been clarified, simplified, and unified around one great love, and who remains steadfast in that love regardless of circumstances.

 

Called to Be Saints

Now comes the part that should speak to all of us.

This holiness, this blazing, weighty, world-altering reality, is not reserved for God alone. It is extended to us as an invitation.

“As he who called you is holy, be holy yourselves in all your conduct; for it is written, ‘You shall be holy, for I am holy’” (1 Peter 1:15–16). Peter is quoting Leviticus, reaching back into the oldest layers of Israel’s covenant life to remind his readers that God has always intended to share His holiness with His people.

This is not a cruel impossible command, like telling a fish to fly. It is a promise wrapped in an imperative.

The God who calls us to holiness is the same God who provides the means.

And what are the means?

Here we must be honest about something. We live in a culture that prizes self-improvement. We are trained to think in terms of strategies, techniques, and measurable outcomes. The "self-help" section at the bookstore is loaded with bestsellers, and clearly, these books haven't delivered entirely, because people keep buying them, trying to find some way to be better, some strategy to improve. When the tactics of one guru reach their limit, they find another, and another. Some of these books are wrapped up in a Christian veneer, promising your "best life now," or some kind of one-size-fits-all solution to whatever ails us. And so when we hear the call to holiness, our instinct is to ask, “What steps do I need to take?”

That instinct is not entirely wrong, but it can lead us astray if we forget the most fundamental truth of the spiritual life: holiness is first a gift before it is a task.

Paul writes to the Corinthians, “To the church of God that is in Corinth, to those sanctified in Christ Jesus, called to be saints” (1 Corinthians 1:2).

Notice the sequence. They are already sanctified, already set apart. And yet they are still called to be saints, still on the way.

Holiness is both a status conferred and a life to be lived. We do not make ourselves holy any more than a branch makes itself bear fruit. But we must remain connected to the vine. “Abide in me as I abide in you,” Jesus says. “Just as the branch cannot bear fruit by itself unless it abides in the vine, neither can you unless you abide in me” (John 15:4).

This is where the two dimensions Aquinas identified become deeply practical.

There's a story about St. Thomas Aquinas. A fellow Dominican brother asked him what one must do to become a saint. He said simply, "Desire it."

The first thing is to genuinely want to be holy. But even this can be easily misunderstood. Mostly because we often ascribe the idea of "the human will" to a kind of inner-strength, mustering up enough determination that we force whatever it is we seek into existence.

Purity is cultivated not by willpower in isolation, but by attention. What do you give your mind to? What do you gaze at, return to, dwell on in the quiet moments?

The heart becomes like what it loves. 

If we fill our inner life with noise, distraction, and triviality, we should not be surprised when our hearts feel cluttered and opaque.

But if we learn to turn our attention, again and again, toward the presence of God, something begins to change. The glass starts to clear. We begin to see.

And firmness is cultivated not by gritting our teeth but by deepening our roots. Every time we pray when we do not feel like praying, every time we choose faithfulness over convenience, every time we return to God after failure instead of running from Him, we are driving our roots deeper into soil that will hold us when the storms come.

Holiness is not the absence of struggle. It is the presence of an anchor.

 

The Streaks on the Glass

Here is the paradox that every person who has ever pursued holiness eventually discovers: the closer you get to the light, the more you see your own imperfections.

Isaiah did not feel unclean until he stood before the throne. The saints throughout history have consistently described themselves as the worst of sinners, not because they were engaged in false humility, but because they had come close enough to the light to see what the rest of us overlook.

This should free us from two traps.

The first is despair. If growing in holiness means becoming more aware of our sinfulness, then the painful awareness of our failures is not a sign that we are moving away from God. It may be a sign that we are moving closer.

The second trap is complacency. If holiness involves both purity and firmness, then there is always deeper to go, always more glass to clean, always more root to grow.

 

Living It Out

So what do we do to grow in holiness day-in-and-day-out, when the alarm goes off and the day begins its familiar rush?

First, begin the day by remembering whose you are. Before you check your phone, before you make your list, take one moment to acknowledge that you belong to the Holy One, and that He has called you by name. Let this truth settle into your bones.

Second, practice the discipline of attention. Several times during the day, stop and ask yourself, “Where is my heart right now? What am I oriented toward?” You do not need to have a mystical experience. You simply need to notice. Noticing is the beginning of purity.

Third, do the next faithful thing. Firmness is not built in dramatic moments. It is built in the small, repeated choices that no one sees. Return the kind word for the harsh one. Keep the promise that has become inconvenient. Sit in silence with God for five minutes even when your mind races. These small acts of fidelity are the roots going deeper.

As St. Thérèse of Lisieux, known for her "Little Way," beautifully put it in her autobiography, Story of a Soul:

"Love proves itself by deeds, so how am I to show my love? Great deeds are forbidden me. The only way I can prove my love is by scattering flowers and these flowers are every little sacrifice, every glance and word, and the doing of the least actions for love."

Finally, when you fail, and you will, do not mistake your failure for the final word. The same God who is holy beyond all imagining is the God who took a burning coal from the altar and touched it to Isaiah’s lips and said, “Your guilt has departed and your sin is blotted out” (Isaiah 6:7). He does not call us to holiness and then abandon us to our own resources. He purifies what He calls. He steadies what He claims.

The streaks on the glass are real. But so is the light that reveals them. And that light is not there to shame you. It is there to make you clean.