Courtesy the Kassig family

“They tell us you have abandoned us and/or don’t care but of course we know you are doing everything you can and more,” Abdul-Rahman Kassig, born Peter Kassig, wrote to his parents, Ed and Paula, when he had been held by the Islamic State in Iraq and al-Sham for several months. He knew that his captors might kill him—“it may very well be coming down to the wire here”—and in the end they did: over the weekend, ISIS released a video of a member of the group displaying Kassig’s severed head. He was twenty-six years old, and from Indiana. In the letter, he’d sought to prepare his parents for that end, and, perhaps, to forestall the visions they might have of his last moments: “Don’t worry Dad, if I do go down, I won’t go thinking anything but what I know to be true. That you and mom love me more than the moon & the stars.”

Kassig was kidnapped delivering medical aid to people affected by the civil war in Syria. He had been a soldier, a Ranger in Iraq, then a college student, and, very briefly, a husband. (The marriage ended in divorce.) Along the way, he took classes to learn to be an emergency medical technician.* On a vacation to Lebanon, where he encountered Syrian refugees, he realized that his medical knowledge was an asset, a gift he could hand to desperate people. Just before he was supposed to go home, he had, as he wrote in an e-mail to family and friends, “the best conversation that I have ever had with my mom. From 4,000 miles away in a shelled out parking lot in Beirut I told her about what I had been involved in over the last week.” He had found his “calling”:

Yesterday my life was laid out on a table in front of me. With only hours left before my scheduled flight back to the United States, I watched people dying right in front of me. I had seen it before and I had walked away before.… I’m just not going to turn my back this time, it’s as simple as that.

“My whole life has led me to this point in time,” he wrote. He stayed, and bandaged wounds, cared for people in clinics, and, just generally, helped. He was drawn across the Syrian border into a zone of both war and jihadi kidnapping. Joshua Hersh, who encountered Kassig when he was working there, wrote that he “didn’t try to convince me that going back was safe, or even wise. But his commitment to the relief project he had embarked on was untempered, and it was clear to me that he would soon go back.” In a wrenching statement posted to Facebook on Sunday, his parents said, “We are incredibly proud of our son for living his life according to his humanitarian calling,” and asked that people donate to a Syrian relief group in lieu of flowers.

Altruism is a mystery, in the best sense of the word, in the same way that love is. It’s not one we always need to solve; often, it leaves us most puzzled about ourselves, about our own lives spread on a table. (Larissa MacFarquhar has written about this.) But there are also two other, more specific mysteries associated with Kassig’s death. One has to do with his conversion to Islam. The other is why this ISIS beheading video did not resemble others.

At some point in his captivity, Peter Kassig, who was raised Methodist, converted to Islam and took the name Abdul-Rahman.* That is what his parents called him publicly when, after a period in which they were trying to quietly work for his release, they began to speak out; they referred to him as Abdul-Rahman Peter Kassig in the statement after his death was confirmed, when it would no longer have been useful; President Obama also used the name Abdul-Rahman, in calling the murder “an act of pure evil.” Kidnappings often include forced conversions—the men who abducted more than two hundred girls from their school in Nigeria claimed that the girls had converted, but no one would hold those children (or adults in similar situations) to religious declarations made under duress. Kassig’s parents have said, through their family Twitter account and other statements, that they believed he was sincere—and he was, by nature, sincere and searching. They were also, as Kassig rightly said in his letter to them, doing everything they could think of to save him. His mother appeared in hijab in video appeals to his captors, and also at a prayer vigil at an Islamic center in Plainfield, Indiana, where the Muslim community rallied around him. Indeed, the Muslim voices advocating for his release were as many and varied as one could get. They included college students in America, refugees in Syria, and even members of the Islamist Al Qaeda affiliate Al Nusra Front, who remembered him as someone who treated wounded rebels, among others. (This may also hint at the mixture of rebel forces.) It didn’t work. Conversion was never protection. It was not ISIS’s goal to make Kassig a Muslim, nor was it in its interest to acknowledge him as one. The group wanted to murder an American, and it did.

This is what Kassig wrote, obliquely, about the questions he must have known his parents had about his conversion, in that letter from captivity:

In terms of my faith, I pray everyday and I am not angry about my situation in that sense. I am in a dogmatically complicated situation here, but I am at peace with my belief.

Kassig’s parents knew him best, and what “dogmatically complicated” and “peace” might mean to him. In the same letter, he said, “I cried a lot in the first few months but a little less now.” The choice for the rest of us, going forward—when deciding, for example, what name to call him, or to entertain the idea that the conversion was part of where Kassig’s life was leading—seems clear: follow Ed and Paula Kassig’s lead, and give them room to think about what God meant to their son.

Then there is the mystery of the video. The others each involved a hostage kneeling in an almost art-directed outdoor setting, reciting a confession, and then having his head cut off with a knife. This one did not. Instead, the ISIS member who stands there with his head calls him Peter Edward Kassig and states that he “doesn’t have much to say. His previous cellmates have already spoken on his behalf.” Before that, as if to make the point that they do, still, film themselves in the act of decapitation, there is footage of ISIS members killing captured Syrian soldiers this way. Perhaps there is footage of Kassig that the group has in reserve. But its absence so far has led to speculation that, as the Times put it, “something may have gone wrong” from ISIS’s perspective during the filming of his murder.