Just under a year ago, the first part of Ian Bell's monumental study of Bob Dylan was published, to general acclaim.

That book took us up to 1975, covering the first 34 years of the grizzled troubadour's creative journey. Now we have a bigger volume, taking us through to the present. There were to be many troughs and wrong turns, unflinchingly described and analysed by Bell. But the conclusion is mellow: we now have a sort of eventide resurgence, marked by that very fine album Tempest. So the book ends with an unlikely suggestion of epiphany.

For the most part the tone is harder and darker than that of the first volume. Bell finds it difficult to be patient with Dylan's moods, his mercenary foibles, his waywardness. He tells the sad little story of Dylan's involvement in a TV commercial for a major lingerie company. Filmed in Venice, this featured the great man with various models slinking around to his song Love Sick. Bell's neat, acerbic comment on this pitiful grotesquery is that "the problem for anyone who cared, even slightly, was not that the artist had sold himself, but that he had sold the song".

Ah, these songs, variously true, beautiful, haunting, bitter, gracious, wise, and from time to time, just plain silly. And so much else too. Bell analyses many of them with gritty panache, wielding a focused, ferocious intelligence that those who admire Dylan - and Bell himself never loses his admiration - can only be grateful for.

As well as the songs we have their creator and his elusive, antic persona. Bell guides us through the falseness, the wrongheaded indulgence, the sloppiness, the bloody mindedness. He also guides us through the last 40 years or so, in terms of both American culture and world politics.

He is good at contexts, but he overdoes the badness of the 1980s. It was, after all, the decade when people such as Vaclav Havel, Lech Walesa and Mikhail Gorbachev came to the fore. And while Bell's distaste for President Ronald Reagan is understandable, we should not forget that when Gorbachev and Reagan met, for the first time, in Geneva in 1985, our world immediately began to be a much safer planet.

Meanwhile Dylan, an authentic artist of global status, continued to refuse to grant his millions of fans, all across the globe, what they were (and still are) yearning for. They turn up, at stadiums and arenas and halls and theatres, hoping for a good show, maybe even a great show, well knowing they are almost certainly going to be disappointed. But they keep turning up. To be a genuine Dylan fan is to be constantly searching for something that is elusive, and often seems abandoned altogether, only for it to reappear somehow, recreated. And, dare I say, resurrected.

Indeed the biggest surprise for me in this book is a theme running right through it: religion. I thought I knew a lot about Dylan, and even understood a fair bit too, but I confess to having been one of those who have talked glibly about Dylan's Christian phase as if it were some neatly contained aberration. Bell confronts this error head on.

He makes it clear, convincingly and forcefully, that Dylan had always been a very religious songwriter. Indeed he shows, beyond doubt, that there was this nagging, persistent theme; as the albums tumbled out they were, in Bell's phrase, flecked and deeply stained with religious imagery. The search for faith was under way for a long time. And then Dylan encountered Jesus, spectacularly, and was born again.

This was for many, though not for this particular reviewer, distasteful. But Bell is not concerned with taste; he analyses. He suggests that while Dylan had always been ripe for faith, when the faith arrived, it did so in almost brutal fashion and rather unpleasantly. Dylan was now a Jew who believed fervently that Christ would be returning. So you believed or you didn't: there was, as he sang, no neutral ground.

What are we to make of the explicitly Christian songs? Bell notes, reasonably, that in the first seriously Christian album, Slow Train Coming, there is no compassion. The tone is triumphalist and hectoring. At the same time Bell writes sympathetically about that later humble and achingly beautiful song, Every Grain Of Sand. As so often Dylan was unpredictable. His Christianity could be harsh and even obnoxious; it could also be gentle and, for me, true.

One of the felicities in this very fine book is Bell's enthusiasm for many lesser known songs. He is seriously angry with Dylan for writing and recording really great songs and then, with utter perversity, leaving them off his albums. So he writes a lot about the "bootleg" albums, where we can find the rich residue of this discarded material. This means that magnificent songs such as Angelina are given their considerable due (if not When The Night Comes Falling From The Sky, a raw, straightforward song that Dylan belts out with extraordinary gusto, like a born-again rocker, if ever there was one).

This book pays the best kind of homage. Never grovelling, never awestruck, always clear-sighted and discerning, and occasionally angry, Bell remains a fan. An alert, realistic and honest one.