We’ve all heard the remarkable stories of victims forgiving their assailants: The father of a young woman murdered by the Green River Killer, the young New York City police officer shot and paralyzed by a teen-ager, the man shot three times by the Aurora, Colorado theater gunman.

Which brings us to Dzhokhar Tsarnaev, the accused Boston Marathon bomber.

One of the most difficult tenets of Christianity for Christians of all stripes to fully embrace is the concept of forgiveness. Why should anyone who deliberately commits a heinous act against me personally, a relative or friend, or society at large, be worthy of forgiveness?

After all, Tsarnaev, 21, faces 30 federal charges in the 2013 Boston Marathon terror bombings that left four dead and more than 260 injured, including 17 people who lost limbs. (Jury selection began Monday.) Forgive that?

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It was a few days after the Boston Marathon bombings when my Honors Seminar Religion and Violence met at the College of the Holy Cross. Holy Cross is in Worcester, about 40 miles from Boston. Many of my students had family and friends who had gone to the marathon, either as spectators or participants.

We had talked about the Aztecs and Al-Qaeda, Crusades and Jihad, the Provisional IRA and Al-Aqsa Martyrs brigade. Along the way we had intense debates about the ethics of collateral damage during warfare, suicide bombings, and the use of weapons of mass destruction.

Those questions involved other places and other people, separated from us by seemingly vast distances of time and space.

Not any more.

The seminar began with students sharing their experiences. One student, whose mother had run the marathon, talked how connected she felt to others, especially through #bostonstrong Twitter messages. Another student shared how everyone on her hall watched the hunt for the Tsarnaev brothers on television, and how everyone cheered when they were caught. There was a sense of community, a feeling of solidarity.

But soon difficult questions began to emerge.

We had studied cycles of violence, reciprocal and unending revenge and retribution. Then talk turned to forgiveness, and one student asked a difficult question: Did our talk about forgiveness run the risk of making a moral decision most appropriately left to the injured and the families and friends of those who were killed?

It was that last question that has remained with me now that Dzhokhar Tsarnaev is coming to trial.

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Catholicism has sophisticated discussions on sin and forgiveness, about the necessity of both contrition and penance. Contrition means that the sinner feels genuine remorse for the sin committed; penance reflects a desire to atone, to make restitution so that the demands of justice are satisfied.

So forgiving someone for a heinous act does not mean they should go unpunished. Separating the spiritual from civil law allows the forgiver to fulfill Christ’s mandate while society can carry out its responsibility to protect innocent citizens.

The most difficult concept of all is the notion of forgiving when the perpetrator has not said he is sorry. Contrition is not a prerequisite for forgiveness; the bloodthirsty Pontius Pilate never apologized for crucifying Jesus.

Catholicism values praying for criminals, such as St. Therese of Lisieux did when she asked God for the repentance of the murderer Henri Pranzini before he faced the guillotine.

After the assassination attempt that nearly claimed his life, John Paul II met with Mehmet Ali Agca and spoke to him as a brother. Agca was eventually released, served jail time in Turkey, and just recently came to Rome to place flowers on the tomb of the man he once tried to kill.

But Catholicism also celebrates seemingly incomprehensible acts of forgiveness, such as St. Maria Goretti’s willingness to pardon Alessandro Serenelli, the man who mortally wounded her. In this sense, forgiveness speaks to the deepest Christian belief that no one lies beyond the mercy of God.

Not even Dzhokhar Tsarnaev.

These stories speak to the transformative power of forgiveness, how forgiveness can bring a new awareness and a new life to those who need it most: the perpetrators of violence who, as Christ said, “do not know what they do.”

Perhaps Tsarnaev will be released in this way. In God’s eyes, the circle closes with the repentance of the sinner.

The problem for us is that we do not have God’s vantage point — or God’s patience.

And so, we need to be released as well.

I was reluctant to talk extensively about the bombing in class — I thought it might be too difficult because feelings were so raw. But a student came to my office and persuaded me that not only did we need to talk about it, we could talk about it.

And talk about it we did — in ways that did not find an easy resolution or avoid difficult questions and feelings.

But one of the realizations that affected us all was that the Boston bombing showed how we were all connected — connected more closely than we thought. And it is in and through these connections that something redemptive can emerge from an act that caused so much pain and suffering.

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In writing to me several days ago, the student who encouraged me to talk about the bombing reflected on how forgiving does not mean forgetting — instead, it requires remembrance, remembrance of what was done, and remembrance of the victims.

But in and through that process of remembering and forgiving, we will find ourselves released in ways that we did not expect or anticipate. This is because the hard journey of forgiveness inevitably forces us to face the ways we need to be healed and forgiven ourselves.