In his book “What’s So Amazing About Grace?” Philip Yancey describes a conference on comparative religions where experts from around the world debated which belief, if any, was unique to the Christian faith. C.S. Lewis happened to enter the room during the discussion. When he was told the topic was Christianity’s unique contribution among world religions, Lewis responded: “Oh, that’s easy. It’s grace.”

Lewis was right. No other religion places grace at its theological center. It was a revolutionary idea; as Mr. Yancey puts it, grace “seems to go against every instinct of humanity.” We are naturally drawn to covenants and karma, to cause and effect, to earning what we receive.

Grace is different. It is the unmerited favor of God, unconditional love given to the undeserving. It’s a difficult concept to understand because it isn’t entirely rational. “Grace defies reason and logic,” as Bono, the lead singer of U2, put it. “Love interrupts, if you like, the consequences of your actions.”

There’s a radical equality at the core of grace. None of us are deserving of God’s grace, so it’s not dependent on social status, wealth or intelligence. There is equality between kings and peasants, the prominent and the unheralded, rule followers and rule breakers.

If you find yourself in the company of people whose hearts have been captured by grace, count yourself lucky. They love us despite our messy lives, stay connected to us through our struggles, always holding out the hope of redemption. When relationships are broken, my wife Cindy told me, it’s grace that causes people not to give up, to extend the invitation to reconnect, to work through misunderstandings with sensitivity and transparency.

You don’t sense hard edges, dogmatism or self-righteous judgment from gracious people. There’s a tenderness about them that opens doors that had previously been bolted shut. People who have been transformed by grace have a special place in their hearts for those living in the shadows of society. They’re easily moved by stories of suffering and step into the breach to heal. And grace properly understood always produces gratitude.

Of course, grace can easily be exploited by people who don’t want to be held accountable for their misdeeds; the theologian Dietrich Bonhoeffer referred to this as “cheap grace.” Nor is it easy to balance grace with the requirements of justice. We obviously can’t organize society entirely around the concept of grace. Yet the problem today is more the absence of grace than its presence.

It’s easy to understand why. Living a grace-filled life is hard. Most of us, when we feel wronged, want payback. Our first impulse, when hurt or offended, is to strike out, justifying our anger in the name of fairness. We forget the words of Edward Herbert (the poet George’s brother), “He that cannot forgive others breaks the bridge over which he must pass himself,” and we forget that only grace can break the cycle of ancient hatreds among peoples. (It is notable that while I have regretted not granting grace to others, I’ve never once regretted extending it.)

When Mr. Yancey was young, he rejected the church for a time because he found so little grace there. There is a tendency among many people of faith to come across as holier than thou, more eager to judge than to forgive. Jesus encountered this throughout his ministry, which helps explain why he was more comfortable in the company of the unclean and reviled, the lowly and the outcast, than religious authorities. The odds are that you know people who have had scars of ungrace inflicted upon them by the Christian church. Yet when we see grace in action — whether in acts of extravagant, indiscriminate love, in radical self-giving, or in showing equanimity in the face of death — it can move us unlike anything else.

In 2014, Steve Hayner, my spiritual confidant, was diagnosed with pancreatic cancer. Upon learning it had spread, Steve wrote, “In all probability, the remainder of my life on this earth is now to be counted in weeks and months.” (He died in January 2015.) Steve acknowledged that pain and death are reminders of the nature of our broken world. Yet he went on to say: “There is a much bigger story of which this is only a tiny part. And it is God’s story of love, hope, forgiveness, reconciliation, and joy. We went into this journey choosing to trust God and to offer our fears to God. We’ve been so grateful for the freedom from fear and the abundance of peace that we have experienced.” He added, “There are, of course, times of discouragement, grief, pain, and wonder. After all, there are a lot of unknowns ahead of us.”

I sent Steve’s reflections to my friend Jonathan Rauch, who responded, “It’s letters like this — the wisdom, the grace — that make me wish I weren’t an atheist.”

When I recently asked Jonathan how, as a nonbeliever, he understood grace and why it inspires us when we see it in others, he told me that grace is “some combination of generosity and magnanimity, kindness and forgiveness, and empathy — all above the ordinary call of duty, and bestowed even (or especially?) when not particularly earned.” We see it demonstrated in heroic ways and in small, everyday contexts, he said. “But I guess, regardless of the context, it’s always at least a little unexpected and out of the ordinary.”

A lot like if the incarnate deity, veiled in flesh, were born in a manger in Bethlehem.

Peter Wehner (@Peter Wehner), a senior fellow at the Ethics and Public Policy Center, served in the previous three Republican administrations and is a contributing opinion writer.