"Gen’lmen, we just havin’ church here." Six words which - directed at me and a fellow soul buff at the Full Gospel Tabernacle church by its chuckling, irrepressible pastor - still cause this writer to blanch after 15 years.

In truth, the sight of two pale Englishmen seated stiffly at the back of his church was probably no great novelty for the Reverend Al Green. A visit to the white A-frame structure in the Whitehaven district, mere shouting distance from Elvis Presley Boulevard, was an obligatory stop on the honky soulboy’s tour of Memphis. For these particular tourists, morever, there was the supplementary pilgrimage to the Royal Recording Studio, the "windowless cave" where Willie Mitchell cut the tracks that made Green a black pop superstar.

I went to worship in Memphis because I too had succumbed to the spell of those records, lost myself in both the breathlessly sexy curlicues of Green’s singing and the earthy, boxed-in crunch of the Mitchell sound. For me, "I Didn’t Know" on 1975’s Al Green is Love was the most ecstatic eight minutes of deep soul on vinyl. And it wasn’t even deep soul per se. It was - like all the records the two men made together with those virtuosi of understatement the Hodges brothers - a supernal blend of downhome and uptown, lo-fi southern grit and whipped-cream Philly topping. It was a key sound of the early ’70s, as intrinsic to my adolescence as T. Rex.

Green, like Sam Cooke and Marvin Gaye, "crossed over". Almost everyone I know has at the very least a copy of Al Green’s Greatest Hits, many more than own an Otis Redding collection. Why? Because Otis was fundamentally one-dimensional, where Al was a changeling, a vocal shape-shifter who within a single performance could flip from comedy to tragedy, from godliness to lubricity, and from male to female and back again.

Al Green was a one-off, which is why one has looked forward to his "story" for so long. Like Cooke’s and Gaye’s, it’s a narrative of inner conflict, of sin and salvation and guns and God - "strong as death, sweet as love," as Green sang it on a little-known masterwork from 1974. In this instance it wasn’t the singer on the end of the gun barrel but a deluded New Jersey housewife who shot herself dead after hurling a pan of boiling grits over Green’s back.

"The Rev. Green, in the bathroom, with the grits..." It turns out that that shocking night in October 1974 wasn’t quite the watershed moment in Green’s c.v. we've been led to believe. 'Take Me to the River' takes pains to stress that Green was already on his way back to his creator when the unhappy Mary Woodson crossed his path. Yet it nevertheless encapsulates the way Green has spent much of his life torn between his love of God and his adoration of women.

"There’s no use trying to deny the obvious," Green notes in his book. "There’s something about me that women find very attractive." Predictably, much of 'Take Me to the River' is written in this bland, pseudo-conversational style, one beloved of As Told To ghosts. It’s strange how everyone - sanctified soulsters and metal mutants alike - winds up with the same "voice" on these printed pages. So many of these tomes read like treatments for Lifetime biopics, with their pat anecdotes and cosily reductive homilies.

I’d so much rather have heard the slightly nutty voice - part Little Richard and part Prince - of the real Rev. Al. Then we might have had a book to stand alongside Chuck Berry’s My Autobiography or even Charles Mingus’ Beneath the Underdog. Too often one can feel Davin Seay filling in missing details in Green’s "voice". All too rare are the genuine moments of revelation, or even just plain insight. Even the accounts of how the famous Hi sound came about are undermined by self-contradiction: one moment Green is claiming that "softening" his vocal style was his idea, the next he’s giving Willie Mitchell the credit.

As Craig Werner notes in his recent A Change is Gonna Come, the Last Soul Man’s return to the ministry "brought the deep soul tradition full circle," taking the music out of the pop marketplace. (The next stop, lest we forget, was disco.) Today we make do with the ersatz emoting of Macy Gray and Shelby Lynne, music that references Green but seldom wrestles with the agonies of choosing between the church and the roadhouse.

We will never see his like again.