Two days after a young man tried to blow up an airliner over Detroit, I flew with my family from Tel Aviv to Boston via Rome. The day was full of long lines, bomb-sniffing dogs, the opening and searching of overfull suitcases and the struggles to close them up again. In Rome, every single person on our flight was patted down and searched. From one end of the day to the other we must have shown our passports 20 times.

Impromptu debates arose as people from all over the world waited in line together. Was it better to search for the explosive device, as the Americans do, or for the bomber, as the Israelis do? Do the airlines need better technology or better training in behavioral screening? Has the war on terror made us more safe or less?

In Rome we waited in a line that for long stretches of time did not move at all. At one point, the man in front of me turned around, looked at me pleadingly and said, “All this because some guy caught his hands on fire? I mean, how vulnerable are we, really?”

As someone who comes close to dissolving into tears every time the plane shudders, I am the wrong person to ask. I feel extremely vulnerable on planes, big and small, in season and out of season. (Luckily, the airlines have a foolproof way of easing the fears of people like me: unutterable boredom. Four hours into the flight, with six more to go, I gave up worrying and watched the movie.)

How vulnerable are we to terrorist attacks, to plane crashes? The odds are in our favor. Our chances of dying in a plane crash are one in 10 million. But when we are hurtling through the air at great heights and great speeds alongside strangers, we are not invulnerable either. I clicked my tongue and rolled my eyes in solidarity with my fellow passenger, but secretly I was glad we were all getting screened.

How vulnerable are we? Bodily vulnerability is the thread that winds through our humanity, linking us to every other creature. So much about us marks our differences—gender, race, religion, sexuality, politics—but bodily vulnerability unites us across differences. It is that rare thing, a true universal. As St. Jerome put it, the one “whom we look down upon, whom we cannot bear to see, the very sight of whom causes us to vomit, is the same as we are, formed with us from the self-same clay, compacted of the same elements. Whatever he suffers, we also can suffer.”

Whatever one of us suffers any of us can suffer. For St. Jerome, this truth about embodied human life was the foundation of a profound solidarity. But solidarity is not inevitable; it must be chosen. Too often we human beings choose to argue for our positions, to wage our battles and to assuage our fears on the bodies of others precisely because we know how vulnerable they are. Whoever talked Umar Abdulmutallab into trying to blow up a plane and himself along with it understood human vulnerability. So did those who ordered the torture at Abu Ghraib. Knowledge of our shared vulnerability often leads not to mercy and solidarity, but to strategic exploitation of the very thing we all share.

Many days we live unaware of our shared vulnerability. We pass each other in the street, we read about each other in the newspaper and on the Internet, and we do not think of how easily we can all be hurt. We learn how vulnerable we are when we experience illness or an accident, a violent act or even just the knowledge that there are those who wish us ill.

The question is not “How vulnerable are we?” but “Now that our sense of vulnerability has been renewed, how will we live?” Will we move toward greater solidarity or greater fear? How will this latest reminder that there are those who wish us harm shape our engagement with the world? How will it shape our response to actions taken in our name, especially if those actions exploit the vulnerability we share with other human beings? What will we choose?

The psalmist says that God’s compassion for us is born of God’s knowledge of our vulnerability: God knows how we were made; God remembers we are dust (Ps. 103:14). Indeed, when God made us, God gave us our vulnerability. But why? Surely God gave us vulnerability as a gift because it means we must turn toward each other. As creatures who are born helpless, who age and move toward certain death, we need each other in profound ways. Even when we fail to rise to the solidarity to which God calls us, the call persists. Through our shared vulnerability, God has placed us in each other’s care.