Explaining belief has always been difficult. How do you explain a love and logic at the heart of the universe when the world is so out of kilter with this? Has free will got us crucified? And what about the dodgy characters who inhabit the tome known as the Bible, who hear the voice of God? Explaining faith is impossible: vision over visibility; instinct over intellect. A songwriter plays a chord with the faith that he will hear the next one in his head.



One of the writers of the psalms was a musician, a harp-player whose talents were required at "the palace" as the only medicine that would still the demons of the moody and insecure King Saul of Israel. It is a thought that still inspires: Marilyn sang for Kennedy, the Spice Girls for Prince Charles.



At the age of 12, I was a fan of David. He felt familiar, like a pop star could feel familiar. The words of the psalms were as poetic as they were religious, and he was a star. Before David could fulfil the prophecy and become the king of Israel, he had to take quite a beating. He was forced into exile and ended up in a cave in some no-name border town facing the collapse of his ego and abandonment by God. But this is where the soap opera got interesting. This is where David was said to have composed his first psalm -- a blues. That's what a lot of the psalms feel like to me, the blues. Man shouting at God -- "My God, my God, why hast thou forsaken me? Why art thou so far from helping me?" (Psalm 22).



I hear echoes of this holy row when un-holy bluesman Robert Johnson howls, "There's a hellhound on my trail" or Van Morrison sings, "Sometimes, I feel like a motherless child." Texas Alexander mimics the psalms in "Justice Blues": "I cried Lord my father, Lord kingdom come. Send me back my woman, then thy will be done." Humorous, sometimes blasphemous, the blues was backslidin' music but, by its very opposition, it flattered the subject of its perfect cousin, gospel.



Abandonment and displacement are the stuff of my favourite psalms. The Psalter may be a font of gospel music, but for me it's despair that the psalmist really reveals and the nature of his special relationship with God. Honesty, even to the point of anger. "How long, Lord? Wilt thou hide thyself forever?" (Psalm 89), or "Answer me when I call" (Psalm 5).



Psalms and hymns were my first taste of inspirational music. I liked the words, but I wasn't sure about the tunes -- with the exception of Psalm 23, "The Lord is my Shepherd." I remember them as droned and chanted rather than sung. But they prepared me for the honesty of John Lennon, the baroque language of Bob Dylan and Leonard Cohen, the open throat of Al Green and Stevie Wonder. When I hear these singers, I am reconnected to a part of me I have no explanation for -- my "soul" I guess.



Words and music did for me what solid, even rigorous, religious argument could never do -- they introduced me to God, not belief in God, more an experiential sense of GOD. Over art, literature, girls, my mates, the way in to my spirit was a combination of words and music. As a result, the Book of Psalms always felt open to me and led me to the poetry of Ecclesiastes, the Song of Solomon, the book of John...My religion could not be fiction, but it had to transcend facts. It could be mystical, but not mythical.



My mother was Protestant, my father Catholic. Anywhere other than Ireland that would be unremarkable. The "Prods" at that time had the better tunes and the Catholics had the better stage-gear. My mate Gavin Friday used to say: "Roman Catholicism is the Glamrock of religion" with its candles and psychedelic colours -- cardinal blues, scarlets and purples -- smoke bombs of incense and the ring of the little bell. The Prods were better at the bigger bells, they could afford them. In Ireland, wealth and Protestantism went together. To have either was to have collaborated with the enemy -- that is, Britain. This did not fly in our house.



After going to Mass at the top of the hill, in Finglas on the north side of Dublin, my father waited outside the little Church of Ireland chapel at the bottom of the hill, where my mother had brought her two sons.



I kept myself awake thinking of the clergyman's daughter and let my eyes dive into the cinema of the stained glass. These Christian artists had invented the movies. Light projected through colour to tell their story. In the Seventies the story was "the Troubles," and the Troubles came through the stained glass, with rocks thrown more in mischief than in anger. But the message was the same: the country was to be divided along sectarian lines. I had a foot in both camps, so my Goliath became religion itself: I began to see religion as the perversion of faith. I began to see God everywhere else. In girls, fun, music, justice and still -- despite the lofty King James translation -- the Scriptures.



I loved these stories for the basest reasons. These were action movies, with some hardcore men and women, the car chases, the casualties, the blood and guts. There was very little kissing.



David was a star, the Elvis of the Bible, if we can believe the chiselling of Michelangelo. And unusually for such a "rock star," with his lust for power, lust for women, lust for life, he had the humility of one who knew his gift worked harder than he ever would. He even danced naked in front of his troops -- the biblical equivalent of the royal walkabout. David was definitely more performance artist than politician.



Anyway, I stopped going to churches and got into a different kind of religion. Don't laugh. That's what being in a rock 'n' roll band is. Showbiz is shamanism, music is worship. Whether it's worship of women or their designer, the world or its destroyer, whether it comes from that ancient place we call soul or simply the spinal cortex, whether the prayers are on fire with a dumb rage or dove-like desire, the smoke goes upwards, to God or something you replace God with -- usually yourself.



Years ago, lost for words and with 40 minutes of recording time left before the end of our studio time, we were still looking for a song to close our third album, War. We wanted to put something explicitly spiritual on the record to balance the politics and romance of it; like Bob Marley or Marvin Gaye would. We thought about the psalms -- Psalm 40. There was some squirming. We were a very "white" rock group, and such plundering of the scriptures was taboo for a white rock group unless it was in the "service of Satan." Psalm 40 is interesting in that it suggests a time in which grace will replace karma, and love will replace the very strict laws of Moses (in other words, fulfil them). I love that thought. David, who committed some of the most selfish as well as selfless acts, was depending on it. That the scriptures are brim full of hustlers, murderers, cowards, adulterers and mercenaries used to shock me. Now it is a source of great comfort.



"40" became the closing song at U2 shows, and on hundreds of occasions, literally hundreds of thousands of people of every size and shape of T-shirt have shouted back the refrain, pinched from Psalm 6: "How long (to sing this song)." I had thought of it as a nagging question, pulling at the hem of an invisible deity whose presence we glimpse only when we act in love. How long hunger? How long hatred? How long until creation grows up and the chaos of its precocious, hell-bent adolescence has been discarded? I thought it odd that the vocalising of such questions could bring such comfort -- to me, too.



But to get back to David, it is not clear how many of these psalms David or his son Solomon really wrote. Some scholars suggest that the royals never dampened their nibs and that there was a host of Holy Ghost writers. Who cares? I didn't buy Leiber and Stoller -- they were just his songwriters. I bought Elvis.



The Book of Psalms, with this introduction by Bono is published tomorrow by Canongate as part of a new series of pocket canons.







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