It seems increasingly likely that Barack Obama and Rowan Williams - alike leaders of institutions with both a national character and a global reach - will be haunted by the same question: had they been able to govern in less hostile circumstances, would they have become the great leaders they initially seemed to be, at least in their supporters’ eyes?

The United States president may yet win another term in 2012. But the disappointments of his first leave many wondering whether a healthy economy could have given Obama the foundation to do what now seems unlikely: point America beyond its culture wars and launch a new era of liberal confidence after the malaise of the George W Bush era.

The term-limit of the Archbishop of Canterbury, the most senior prelate of the Church of England and worldwide Anglican Communion, is less precisely defined - though his retirement, after almost nine years in the position, is reportedly imminent.

In his case, the counterfactual tends to go as follows. If the internal crisis over homosexuality had not blown up so dramatically, forcing him into damage-limitation mode and also leading him to suppress his own liberal instincts, could Rowan Williams have pointed Anglicanism beyond its own culture wars by articulating a vision both liberal and traditional? Could he then have renewed the Church of England, as well as taking the Communion in a progressive direction?

The establishment fix

Yet such questions assume rather a lot. In particular, that Williams had a clear agenda for the renewal of the Church from which he was regrettably blown off course. This in turn suggests that the standard liberal narrative of disappointment at Williams is inadequate. For it falsely supposes that bold liberalism on the gay issue is the essence of reforming vision: if only he had resolutely defended gay rights, all would be well. But in reality the Church of England and the Anglican Communion face deep-rooted challenges that have very little to do with the dispute over sexuality. The real cause for disappointment is that Williams failed to confront these challenges.

What are these deep-rooted challenges? They centre on the complex relationship between the Church of England and the rest of the Anglican Communion. The Communion of course arose from the British empire; an imperial state-church gave rise to satellite churches, which became independent, non-established churches in new states. The history of empire fades very slowly; in a sense it still hinders the development of this international Christian body (which does not call itself a church but a communion of churches, or ecclesial provinces). To a very large extent the Communion still finds its coherence in the imperial centrality of the Church of England. I suggest that it cannot easily move on from its imperial past while the Church of England remains strongly in tune with that past - by virtue of remaining established. Also, of course, there is a purely domestic case for disestablishment.

Rowan Williams's origin in the disestablished church in Wales meant that he was well placed to start this conversation. Without explicitly advocating disestablishment, he could have put the issue on the table. He could have explained, in his capacity as leader of the Anglican Communion, that establishment is not essential to Anglicanism, but rather anomalous, and that the establishment of the mother-church might be seen as a structural problem, a barrier to Anglican coherence. If the Communion is to become stronger, maybe this local quirk must be rethought.

I am not saying that Williams should have suddenly solved this huge, centuries-old problem, but he should have nudged the Church of England towards understanding the situation. He should have helped it to see itself less as a national established church, more as part of an international phenomenon. He had the opportunity to coax the Church of England towards this "paradigm shift"; to show it that its future is as one part of an international religious body, the Anglican Communion. But many diverse complexities surround this process, and over the last decade they all surfaced together, overwhelming any reforming intentions that Williams may have harboured.

The double constraint

It must first be noted that Williams’ position on the establishment of the Church of England has always been somewhere between nuanced and muddled. From one angle he sees it as a barrier to an authentic, international Anglican ecclesiology (he is sympathetic to the Anglo-Catholic tradition that sees establishment as an insult to the Church’s authority). But from another angle he sees establishment as a valuable defence against secular liberalism and individualistic capitalism: it is a statement that religion remains fundamental to society.

Before his appointment to Canterbury, the former perspective just about dominated: he was a very tentative advocate of disestablishment. This changed after his appointment, and not just because of his new role. The main factor was 9/11, and the high-profile debate about the place of religion in society that ensued.

The atmosphere of this debate was nervy, defensive; not conducive to the floating of reforming ideas. Many religious voices warned of a new aggressive secular liberalism, and insisted that establishment was a crucial bulwark in an uncertain time. Williams went with the flow: he foregrounded the "anti-secular liberal" side of his thought. The new mood of polarisatio, between "religion" and "secular liberalism" made it almost inevitable that the Church of England would retreat into conservative habits, and make liberal qualms seem disloyal. This conservative mood was also expressed in the arena of church schools, which were developed in a direction that greatly irked secular liberals (admission was increasingly restricted to active churchgoers). In this new era of religious politics, Williams perhaps had little choice but to make more of his conservative aspect, and to keep disestablishment far from the table.

In his previous career Williams had balanced conservative with liberal impulses. His conservatism was expressed in his attachment to Catholic forms and ideas, and his opposition to certain currents of liberal theology. His liberalism was expressed in a leftish, anti-Tory, gently anti-establishment attitude, and also in his reformist position on the ordination of homosexuals.

It was inevitable that appointment to Canterbury would to some extent encourage the exaggeration of his conservatism and the diminution of his liberalism. But external circumstances meant that this happened to a remarkable degree. Most obviously, he found it necessary to suspend his liberalism on homosexuality. With most provinces of the Communion violently opposed to the ordination of homosexuals, he had to represent the majority, and reprimand the American church for choosing a homosexual as a bishop in 2003.

The whole saga has had a disastrous impact on the aforementioned paradigm-shift: the process by which the Church of England moves towards seeing itself less as a national church, more as part of an international body. The crisis has made the Communion seem a retrograde force in the eyes of the liberal majority of English Anglicans, a vehicle for fundamentalism. It seems to show that the best defence of liberal Anglicanism remains the good old established Church.

It is hard to imagine how Williams could have defied these two mighty forces that beset him: the new conservatism that followed 9/11, and the explosion of anti-gay sentiment in the Communion that followed the election of Gene Robinson as bishop of New Hampshire in 2003. But it is worth imagining what he might have attempted, had they been absent.

Without these constraints, he could have encouraged the Church of England to look at itself in the light of international Anglicanism. He could have shown it that its entanglement in national cultural politics might be a distraction from its essential religious purpose. As a semi-outsider, he was well placed to say that English Anglicanism carries unnecessary baggage that may impede evangelism. It entails a particular conception of religious politics, one that is very widely seen as dated, illiberal. He could have put the question: has this historical inheritance become a distraction, even a subtle form of idolatry? Consider the wider Communion, he could have said: it proves that establishment is inessential to Anglicanism.

The surprising truth

So the need remains, for a visionary archbishop of Canterbury. Such a figure would begin to wrest the Church of England from its ancient political entanglement, using the Anglican Communion. He would say that Anglicanism is now essentially a post-establishment tradition. He would tell the parent-church to learn from its children. By this means he would encourage the English to look again at the primary business of Christianity: the ritual response to Jesus Christ, and the creation of community around this form of culture. He would liberate Anglicanism from its historical involvement in state power - or at least announce that this is the project of our time.

Would this lead to a renewal of the Church of England? It is impossible to say whether it would become more successful in attracting people. But it would become purer, purged of its complicated accretions.

At the risk of sounding faux-naïve, English Christianity must be de-complicated, shown to be surprisingly simple. All the stuff that gets in the way of the communication of Jesus Christ must be reformed away, or at least identified as secondary, dispensable. This is a difficult process, which entails the renunciation of inherited power, but only through such a process can this tradition find new coherence, and new authenticity.