If you have listened to teen-agers lately -- I get the mind-thrill every evening at dinner, times three -- be comforted, not alarmed, when they speak of rock music in one sentence and Amnesty International in the next. They're U2 kids.

U2 is the band from Dublin whose sixth album, ''The Joshua Tree,'' was at the top of Billboard's chart for nine weeks this spring. In April the four Irish rockers were on the cover of Time. This week, Bono Hewson, the band's singer and songwriter, is on the front of Rolling Stone, with a 3,000-word interview inside. The group is currently touring the United States, playing in 46 stadiums and arenas with ticket sales already beyond 1.5 million.

What's it all about? U2 produces music the way Patrick Kavanagh did poetry and Sean O'Casey prose: with a passion that touches the heart and a purpose that raises the mind. The other evening in Washington's Robert F. Kennedy Stadium, 45,000 people -- most of them high-school and college students -- assembled for a concert in which U2 sang of Martin Luther King Jr., El Salvador and Northern Ireland.

One of the loudest thunderings of applause came when Bono Hewson spoke of Amnesty International and of his commitment to getting political prisoners out of the world's jails. Spontaneously, two members of the audience came onstage and unfurled a wide banner lettered with one word, AMNESTY, and painted with the peace symbol. That evoked another roar of approval, the sustained sound echoing in the stadium like a rockslide in a canyon.

When kids pile into a car and say they are heading into the night for a rock concert, some parents either start phoning other parents to spread the worry or silently thank Tipper Gore for trying to force Frank Zappa to stop singing dirty. There's another option for parents, at least if it's a U2 concert: Go, look and listen. Some of the chord-crashing music jackhammers into your ears and often the words are about as clear as primal screaming. But U2, like no other musicians today, are telling the young that they owe a debt to life.

U2 echoes the message of King: be other-centered, not self-centered. Someone in the audience must be listening. In the past year that U2 has made Amnesty International part of the evening, U.S. membership has increased by 100,000 to 265,000. The number of Amnesty chapters in high schools and colleges has gone from 250 to 510.

The band doesn't hype itself as world-savers. They are Irish, after all, from a land with irreverence for preaching. ''There is a radical side to Christianity that I am attracted to,'' Bono Hewson says in Rolling Stone. ''And I think without a commitment to social justice it is empty. Are they putting money into AIDS research? Are they investing in hospitals so the lame can walk? So the blind can see? Is there a commitment to the poorly fed? Why are people left on the side of the road in the United States? Why, in the West, do we spend so much money on extending the arms race instead of wiping out malaria, which could be eradicated given 10 minutes' worth of the world's arms budget?''

Some would put that down as the standard line of the utopian left -- or worse, as plasma from a collective bleeding liberal heart. Such dismissals would be the rants of cynics who don't want the young to have their chance at reforming the world: Give up, it's hopeless. Or if you won't give up, listen to the experts, not rock stars and least of all Irish rock stars.

Would U2 buy that line, considering it is part of an industry that gives us the Sex Pistols, Boy George, Twisted Sister and sourpusses like Mick Jagger? ''No longer do fans of music run the music business,'' Bono says. ''Fans of money run the music business.''

U2 is distinct, first, because it has worked for a decade -- since four Irish teen-agers came together in 1978 in a Dublin kitchen -- to create hauntingly beautiful sounds and, second, because U2's call to action begins with the inner self. ''I'm more interested in . . . a revolution of love,'' Bono says. ''I believe that if you want to start a revolution, you'd better start {it} in your own home and your own way of thinking and of relating to the men and women around you.''

In Washington, Patty Smith, a Georgetown University student, wrote to a friend about ''the peaceful experience of last night's U2 concert. With the stadium in total darkness, the night pierced by the lights of thousands of lighters and tens of thousands of voices raised in one song, there was an eerie, peaceful, almost religious sense to it. The song was the refrain to a ballad; the audience was singing, not to entice the band into coming back -- we knew it wouldn't. We were singing for ourselves.''

A dreamy idealist? A self-centered college kid? No.