The future resides with the young. We have plenty of cause for hope—or for concern, depending on whom they listen to.

The number of young people in many of the world’s most volatile countries is growing exponentially. Almost half of those in the Palestinian territories are under 15, as are a third of India’s 1 billion plus. The median age in Iraq, Kenya, Afghanistan, Egypt, and Pakistan is under 25.

Rapid change, social upheaval, and insecurity have created a psychological crisis that religious extremists of all persuasions exploit by offering youths a sense of mission and paths to leadership.

As executive director of Interfaith Youth Core, Eboo Patel fosters international relationships based on mutual respect and shared values between religious young people. At the PUSH conference this summer in Minneapolis, Patel described the “youth bulge” and the increasing social complexity that shapes its attitudes, from evolving gender roles to disappearing traditional occupations to exposure to other cultures.

Meanwhile, pluralist societies such as our own tend to patronize the young with a pat on the head and no real responsibility. Young people, Patel asserts, want clear identity and powerful impact, and our challenge is how to nurture that in a diverse, democratic society.

One place for us to begin is to recognize that we need battalions of young, energized, interconnected, tech-savvy idealists, because they are the ones equipped to solve today’s daunting challenges. Everywhere I go, I encounter brilliant young people who are full of vision and entrepreneurial spirit. More and more, they give me cause for hope.

I got an extra dose of optimism when my middle son, Oliver, graduated from Wesleyan University in Middletown, Connecticut, in May. It was a perfect early summer day, and the excitement of graduation was heightened by the fact that Barack Obama was the last-minute replacement for an ailing Ted Kennedy.

Obama delivered a stirring call to service: “You can take your diploma, walk off this stage, and chase only after the big house and the nice suits and all the other things that our money culture says you should buy. . . . But I hope you don’t . . . because our individual salvation depends on collective salvation. . . . At a time of so much cynicism and so much doubt, we need you to make us believe again.”