20 years and the last seven days: U2 have gone through a whole heavenhell of a lot to get here. One can only guess at Bono’s state of mind, high on the euphoria of playing the most ecstatic shows of his band’s career, drained from the freeze-dried exhaustion of flying home to Dublin from all points around Europe to endure the dim purgatories every son goes through when his father is dying. And now, the day after Bob Hewson’s funeral, he’s here, with half the country trying to read his face. Sometimes, in the teeth of grief, all you want is to be surrounded by noise. A Patti Smith line: "I feel upset/Let’s do some celebratin’ …

U2 homecomings are always monumental, but the backdrop to tonight’s gig was off the scale. It also put some hard questions to the observer. Such as, is it voyeurism to watch a man sing about his grief on a stage in front of 80,000 people? Or is it one of the things rock ‘n’ roll is best at – making magic out of loss?

It asked a lot about the human condition, this show. A grieving man singing loud, sad songs to a huge crowd on a Saturday night. Bunches of socialites whining about the colour of their laminates to the sound of a song like ‘Kite’. Or more to the point, times when the crowd seemed to carry Bono, Bono carried the crowd, the band carried Bono and Bono carried the band. We get to carry each other…

‘Sgt Peppers’ was the cue ("It was 20 years ago today"), as a half moon hung in the pale blue and U2 lit a fire under ‘Elevation’, all war whoops and noise loops, with Bono’s plea of, "I need you to elevate me here" ringing all too true over the Stooges/Mary Chain din generated by Edge.

The atmosphere has changed at U2 home gigs. In ways that seemed true in previous years, the band no longer belongs to the people, nor the people to the band. Things have accelerated, there’s more static, more distractions, and consequently the stage at Slane sometimes looked like a lonely place to be. Because of/in spite of this, ‘Beautiful Day’ was astounding. Bono has often spoken of this tune as the parable of a guy who loses the world but gains himself; tonight, its blazing refrain of "What you don’t have/You don’t need it now" transcended everything. Chills.

"Jesus, meet Judas," Bono offered by way of segue, and the first of the night’s morality plays unfolded in ‘Until The End Of The World’. Here, the singer looked like his heart was being held together with leather binding and not much else as he enacted the matador/minotaur routine with Edge on the walkway, lying on his back, kicking hell out of the latter’s guitar.

This was total theatre, although I’m not sure the set’s transition from indoor to outdoor was always as easy. But what you lose in spectacle, you gain in feeling. There were Spielberg moments for sure, but bereft of Pop’s whistles and bells, stripped to four monochrome screens and an understated light show, the band leaned hard on the songs and the spirit for sustenance.

As a result, Bono seemed to locate new sense in old lines ("I will be with you again" from ‘New Year’s Day’), strung out between exhaustion and elation. Forced into emergency mode, Adam and Larry played rearguard action, less at liberty to stretch, covering their frontman (at one point, Bono sang the middle eight of ‘Stuck In A Moment’ with his head resting on Adam’s back). But while there were one or two grey areas in the set list – ‘A Sort Of Homecoming’ sounded unconfident – there were also scores of moments few spectators will ever forget.

Certainly ‘Kite’ may never sound the same again. "I thought I wrote this for my own kids, but I think my old man wrote it for me and my brother," Bono said after thanking God for taking his father from his sickness. Then, these lines:

"Something is about to give

I can feel it comin’

I think I know what it is

I’m not afraid to die

I’m not afraid to live

And when I’m flat on my back

I hope to feel like I did…"

Torches burned, smoke obscured the moon, and the singer’s voice cracked: "I know that this is not goodbye". It wasn’t about life and death and rock ‘n’ roll. It was more important than that.

U2 spent the next couple of tunes, ‘I Will Follow’ and ‘Sunday Bloody Sunday’, getting re-orientated, reconciling the political and personal, trying to find a line into the heart of the music. When they located it – with ‘Wake Up Dead Man’ – the fucking hairs stood up on the back of my neck.

A couple of tunes later, after name-checking Phil Lynott, reminiscing about the last time they played Slane ("We were crap") and jamming out ‘Dancing In the Moonlight’, Bono and Edge essayed a glistening ‘Staring At The Sun’, a song which has gained in stature out of the Pop clamour.

‘Bad’ took U2 back into cinemascope mode, with ad-libs from the Stones’ ‘Fool To Cry’ and Coldplay’s ‘Yellow’, but really, the show started all over again with that Close Encounters of rock ‘n’ roll songs, ‘Where The Streets Have No Name’, only to end minutes later with ‘Pride’.

The encores started with a headfuck and ended with heart palpitations. Over a gospel proclamation of (I think) "Evil one", the screens offered NRA president Charlton Heston’s infamous remarks, "There are no good or bad guns. A gun in the hands of a good man is no danger to anyone . . . except bad people." Cue footage of what looked like a toddler picking a revolver up off the floor, soundtracked by the oxblood noise of ‘Bullet The Blue Sky’, Edge’s guitar puking up metal over a rap about slappin’ down those dollar bills at Wal-Mart. Then it got weird, with the singer replaying those Jesus/Judas dialogues as a black pageant starring Lennon and Chapman, hammering home his point with the couplet, "Pull the trigger/Rock ‘n’ roll nigger".

Out of this nightmare, a collective sigh at the first notes of ‘With Or Without You’. Encoded in the DNA of this tune you can find all the reasons why U2 made it this far – in that line "You give yourself away", in Edge’s chimes, in the wordless cry made as the drums kick in.

Then, ‘One’, the song that saved U2, a heart to heart between lover and lover, father and son, a song riddled with so many dualities it shouldn’t be this uplifting. Bono prefaced it by thanking his father for his voice, before putting it to use with that "Can you hear me comin’?" refrain which always seems to have a direct line to the tear ducts. From there, acoustic fragments of ‘When Will I See You Again’, a sigh of a love song reinterpreted as gospel.

Once more, Bono invoked his old man’s name as the band struck up their last song, ‘Walk On’. All That You Can’t Leave Behind has become something of a testimony for absent friends (Joey Ramone was invoked earlier in ‘In A Little While’), but tonight, all the songs had to point in one direction. "Leave it behind," Bono sang, as the litany of the song’s final section got caught and tossed by the breezes: "You’ve got to leave it behind."