The remarkable passages from Rowan Williams's valedictory work as archbishop of Canterbury revealed in today's Observer carry much of the intellectual energy that led to such high hopes accompanying his arrival in Lambeth Palace nearly 10 years ago.Back then Williams said: "You'd have to be a maniac not to have doubts about accepting" the job of leading the Church of England.
The difficulties and struggles of the following decade mean that publication of Faith in the Public Square in September will be a moment of catharsis for Williams, rather than an unequivocal celebration of his time in office.
After a decade of messy compromise and argument over issues of gender and sexuality, as the archbishop battled to keep the worldwide Anglican communion together, this is "Rowan Unplugged", the work of a man who finally feels liberated to say what he thinks.
When Williams was chosen as the 104th archbishop of Canterbury, he was showered with compliments from fellow churchmen and politicians alike. The strong opposition to his appointment that had been voiced by hardline evangelical conservatives during his campaign melted away amid excitement and a sense of expectation.
The prevailing view was that Williams was a man who could make the Church of England seem relevant and interesting in an age of technological advance, widespread cynicism and fear.
The world was still reverberating from the 9/11 terrorist attacks in the United States and President George Bush and Tony Blair were preparing for war in Iraq. In the words of his biographer, Rupert Shortt, Williams was a formidable intellectual who seemed right for the time. He was, Shortt wrote, the "most distinguished occupant of Augustine's chair since St Anselm (1033-1109), who framed the ontological argument for God's existence," no less.
It was clear from the start that whatever Williams did in office, he would make waves. He was already known for thinking profound and complex thoughts aloud – often oblivious to how they could be boiled down into inflammatory newspaper headlines.
The Catholic newspaper the Tablet newspaper described him in 2002 as a "prophet and a theologian" who was certainly not a "safe" establishment bet. The paper predicted that if Blair and Bush did go to war against Saddam Hussein, then Williams would certainly take them on.
Long before moving into Lambeth Palace, Williams had won a reputation in church circles as a liberal, backing gay rights and female ordination.
Once in post, however, he often seemed keener to preserve unity than risk widening splits.
When the dispute over gay priests was threatening to tear the church in two in 2003, Williams initially proposed Jeffrey John, who is gay, as Bishop of Reading. But following evangelical protests he changed direction and asked him to stand down.
Despite attempts to find common ground on the wider political, social and moral issues of the day, Williams has sometimes found himself inadvertently drawn into confrontation and controversy.
In October 2002 he signed a petition against the Iraq war that said it was contrary to Christian teaching, and in 2004 he wrote to Blair to express his concern about government policy and the conduct of some British troops. The following year he was ambushed on the Today programme by John Humphrys, who rounded off a long discussion about gay clergy by asking if Williams saw the Iraq war as "immoral".
After a pause of 12 seconds – which a furious Lambeth Palace tried to have edited out before the recorded discussion was aired – Williams certainly did not disagree, saying "immoral… was a short word for a very long discussion".
In 2008 he faced a huge backlash in the right-wing press, which had picked up on a rather arcane speech that appeared to endorse the adoption of some aspects of Islamic sharia law in Britain.
Williams argued that other religions enjoyed tolerance of their own laws and called for "constructive accommodation" with Muslim practice in areas such as marital disputes. The year before, in an interview with the British Muslim magazine Emel, he caused a similar stir, comparing British Muslims to good Samaritans and arguing that the US had lost the moral high ground since 9/11.
In Faith in the Public Square, he emphasises a different theme, stating that "Muslims must make clear that their loyalty is straightforward modern political loyalty to the nation state", rather than an "overriding loyalty to the International Muslim Community (the Umma)".
Williams rode into an unanticipated political storm in June last year when guest editing the New Statesman. He wrote that David Cameron and Nick Clegg were driving through "radical
policies for which no one voted", prompting a furious response within the Conservative party.
He also criticised the chancellor, George Osborne, for blaming the economic difficulties and resulting need for austerity on the last Labour administration.
"It isn't enough to respond with what sounds like a mixture of 'this is the last government's legacy,' and 'we'd like to do more, but just wait until the economy recovers a bit'," he said.
On the coalition's welfare reforms he complained of a "quiet resurgence of the seductive language of 'deserving' and 'undeserving' poor".
As the Observer reveals today, Williams is turning up the volume still further as he leaves office.
In Faith in the Public Square, Williams roundly denounces wanton materialism, excessive military spending and the worship of consumer goods.
His critique of the coalition goes much further than before, arguing that Cameron's supposedly defining concept of the "big society" lacks any clear definition and is seen by the public as a cover for the withdrawal of the state from its responsibility to the most vulnerable in society.
The book is laced with outspoken criticisms of economic and political values that drive advanced western societies. It criticises assumptions that are now built into life in the 21st century – such as the idea that economic growth is by definition a good thing. It is the church's role, Williams believes, to ask why this should necessarily be the case.
"At the individual and the national level, we have to question what we mean by growth," he writes. "The ability to produce more and more consumer goods (not to mention financial products) is in itself an entirely mechanical measure of wealth. It sets up a vicious cycle in which it is necessary all the time to create new demand for goods and thus new demands on a limited material environment for energy sources and raw materials."
"By the hectic inflation of demand it creates personal anxiety and rivalry. By systematically depleting the resources of the planet, it systematically destroys the basis for long-term wellbeing. In a nutshell, it is investing in the wrong things."
After his retirement at the end of the year, Williams will become master of Magdalene College, Cambridge. He says he will say nothing in public to make life awkward for his successor. But he is unlikely to stay quiet for long.
Faith in the Public Square will be published by Bloomsbury on 21 September, price £20