Opinion by the Rev. James Martin, Special to CNN

(CNN) - I could barely look at the photos, but I knew that I must.

Wednesday in St. Peter’s Square, Pope Francis met, embraced and kissed a man suffering from a rare disease called neurofibromatosis, a painful and disfiguring skin condition.

Photos of the Pope hugging a man whose face was blanketed with tumors struck a deep chord in people across the world. When I posted them to my public Facebook page, I received almost 300 comments in the space of a day.

Why do these photos speak to so many people so profoundly? Let me suggest three reasons.

For the Christian, the image of the Pope’s embrace calls up memories of the man whose name Archbishop Jorge Mario Bergoglio chose after his election as Pope: St. Francis of Assisi.

As a young man, riding his horse one day outside of Assisi, Francis came upon a leper, a person suffering from one of the many skin diseases common in the early 13th century.

From childhood Francis had had a horror of lepers. Yet because of an earlier dream in which God had asked Francis to change his life, the formerly dissolute youth saw that something new was being asked of him. He dismounted his horse, pressed a coin into the leper’s hand and kissed him.

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When he jumped back on his horse and turned to wave farewell, Francis saw that the leper had disappeared - legend has it that it was Christ.

It was a turning point in the life of Francis of Assisi; from then on he would devote himself to the poor and marginalized. He had embraced, to use Mother Teresa’s famous expression, “Christ in distressing disguise.”

The Pope has done the same; Christians recognize this on a deep level.

More broadly, the Pope’s embrace recalls images of Jesus’ healing of lepers, again a blanket term for a variety of skin diseases common in first-century Judea and Galilee.

In a frequent theme of the Gospels, Jesus of Nazareth not only heals but touches people considered “unclean,” dangerous to be around and unworthy of inclusion in society.

In the Gospel of Mark, a leper begs Jesus for healing, by saying, “If you choose, you can make me clean.”

Mark’s Gospel tells what happened next: “Moved with pity, Jesus stretched out his hand and said to him, ‘I do choose. Be made clean.’ Immediately the leprosy left him and he was made clean.”

But the English translation of this powerful story is weak indeed.

The original Greek word for “moved with pity” is the Greek "splagchnistheis."

This means that Jesus felt compassion in his bowels, the place where the ancients believed that the emotions resided. In other words, Jesus felt it in his guts. This is the kind of compassion we are called to have and to express. This is the kind of compassion we see in the photo of the Pope’s embrace.

Even more broadly, for believers, the Pope’s kiss reminds us of God. This is the way God loves us. God loves us in all our pain, in all our struggles, in all our humanity.

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Few of us suffer from such a terrible disease as does the man in the photo; not many of us are physically disfigured. But many of us feel internally disfigured - unworthy of unconditional love. Yet God wants nothing more than to embrace us as tightly as the Pope’s embrace.

In this photo, on a level deeper than we might even be able to recognize, we see an image of God.

In the Parable of the Prodigal Son, Jesus’ tale of a father’s reconciliation with a son, there is a wonderful line. When the wayward son returns home, after squandering his inheritance on a life of debauchery, Jesus says that the father, seeing his son from afar, rushes out to greet him. The original Greek then describes the father doing something wonderful.

The English translation of Luke’s Gospel says that the father “ran and put his arms around him and kissed him.” Again, a literal translation from the original Greek is more beautiful, and will resonate with anyone who sees the photos. "Kai dramōn epepesen epi ton trachēlon autou kai katephilēsen auton" can be translated as “And running, he fell upon his neck and fervently kissed him.”

Do you ever wonder what God’s love is like? Look at Jesus. Look at St. Francis of Assisi. And look at the Pope.

The Rev. James Martin is a Jesuit priest and editor at large of America magazine, and author of "The Jesuit Guide to (Almost) Everything." His book "Jesus: A Pilgrimage" will be released in March.