Islam is not a violent religion, and only a minority of its followers have embraced fundamentalism, Pope Francis said in an overnight press conference.
"I think it is neither true nor right to say that Islam is [a] terrorist [religion]," Francis said on the plane back from Poland, according to a transcript by Vatican Radio.
The pope was in Poland July 27-31 for World Youth Day, a week-long event attended by over a million pilgrims. A day before he left, an elderly Catholic priest was killed in Northern France during Mass, in an attack that was claimed by the Islamic State.
"One thing is true: I think that in nearly all religions there is always a small group of fundamentalists," the pontiff noted, adding that it was a problem also for Christians.
"If I had to talk about Muslim violence, I would have to also talk about Catholic violence. Not all Muslims are violent. Not all Catholics are violent," he added.
He said Europeans should reflect on what drives disaffected youth to join the Islamic State terrorist group.
"I ask myself: how many young people, how many young people, whom we Europeans have left empty of ideals, have no jobs and turn to drugs, alcohol or enrol themselves in fundamentalist groups," Francis lamented.