If a week is a long time in politics, eight years is an epoch in the modern papacy.

The shock resignation - the first in more than 600 years - of the 85-year-old Pope Benedict XVI comes at the end of an eight-year rule of the Holy See that has seen the foundations of the Catholic Church shaken as never before.

A man most defined by his strict adherence to the oldest and most challenged portions of Church doctrine was always going to struggle to unite a global faith that was already reeling from what His Holiness himself had called the "cloud of filth" of a decades-long sexual abuse scandal that rose to the very feet of the Vatican's cosseted leadership.

In fact, the allegations involved the man himself. As Joseph Ratzinger, he served as the Archbishop of Munich and Freising in the late 70s and early 80s and was said to have personally approved the transfer of a priest accused of molestation to his diocese in order to receive treatment and therapy.

But at a time when faith and its influence of the lives on non-believers was being questioned amid clashes between Muslims and Christians in Asia, the Middle East, Africa and elsewhere - not to mention the existential nature of its threat following the attacks on the World Trade Centre in 2001 - Pope Benedict chose to define his papacy with the challenge of attacking what he called "aggressive" forms of secularism around the world.

Yet despite his reputation - largely earned during the many years he worked closely with his predecessor, Pope John Paul II, as head of the Congregation for the Doctrine of the Faith - Pope Benedict showed a surprising flexibility when it came to dealing with the secular world.

Cynics may argue he had little choice, but it has to be conceded that his efforts to bind the Vatican bank to European Union rules on money laundering after a series of financial scandals at the Holy See's bank were historic departures from previous Vatican "Droit de Seigneur".

Equally, his views on some forms of contraception showed signs of secular influence when he told the German journalist Peter Seewald that condoms, if used to prevent the spread of Aids, may be considered "a first step in a movement toward a different way, a more human way of living sexuality."

As mild as it may seem in print, the mere reference to a change in Church doctrine with respect to contraception is perhaps one of the most significant developments in papal thinking for many decades. Not to mention a seemingly powerful contraction to his earlier views on the "dictatorship of relativism".

He was also unafraid to criticise his own faith - and by extension challenge the notion of papal infallibility - when we castigated officials for "not being vigilant enough" during the Church's response to allegations of clerical sexual abuse.

It was an extraordinary move, particularly given the pontiff's earlier letter, De delictis gravioribus, written when he was Cardinal Bishop of Velletri-Segni, clarified the Church's view that internal investigations remain confidential.

"In the name of tolerance, tolerance is being abolished," His Holiness told Seewald. "This is a real threat we face."

The reluctant pontiff faced that secular challenge in a remarkably liberal, if agonisingly slow, way. And for a man who had a geninue hatred of moral relatavism, there's more than a touch of irony in the fact that the sucess of his legacy can only be measured in terms relative to those of his more conservative predecessors.

What remains to be seen is whether his slow steps towards a flexible approach will be taken up by his successors.