Much of the confusion around U2’s faith stems from the fact that they’ve never been an “officially” Christian rock band. The ambiguity goes back to the band’s origins, in the Dublin of the late seventies, during the Troubles. In a country divided along sectarian lines, little about organized religion was attractive. U2 were teen-agers when they got together (Larry Mullen, Jr., the drummer, was just fourteen), but they were beginning to see outside of the faith traditions of their families. Bono’s father was a Catholic, his mother an Anglican. Adam Clayton (the bassist, English) and David Evans (the Edge, Welsh) came from Protestant backgrounds; Mullen had Irish-Catholic parents. In “North Side Story: U2 in Dublin, 1978-1983,” Niall Stokes, the editor of the Irish music magazine Hot Press, writes that the members of U2 were “primed” to ask what it meant to be Irish. They were “as close as you could get at the time, in an Ireland that was monocultural to an extraordinary degree, to a licorice all-sorts of nationalities and faiths.”

Their break with organized religion was probably inevitable. But it was still traumatic, which is perhaps why almost every U2 album contains a song about their decision to belong to a band rather than a church. (“One,” for example, is about the challenges of joining together with your friends to try and find God on your own.) Greg Garrett, an English professor at Baylor, a Baptist university in Waco, Texas, explains U2’s lack of religious identification in his book “We Get to Carry Each Other: The Gospel According to U2.” In high school, Bono, the Edge, and Mullen grew close to a faith community called Shalom, whose members Bono has described as living on the Dublin streets “like first-century Christians.” The group was a big presence in their lives during the recording of U2’s first two albums, “Boy” and “October” (“Gloria,” the best song on “October,” has a liturgical chorus, sung in Latin). The turning point came just as the “October” tour was set to begin: the Edge announced that he wanted to leave U2, because the twin demands of piety and rock stardom could not be reconciled. (“If God had something to say about this tour, he should have raised his hand a little earlier,” the band’s manager, Paul McGuinness, said.) Ultimately, of course, U2 stayed together: Bono, Mullen, and the Edge left Shalom. “I realized it was bullshit, that what these people were getting close to … was denial, rather than willful surrender,” Bono told an interviewer.