The first leader of the world's Roman Catholics to come from Latin America has been credited with bringing a breath of fresh air to the way the Church relates to a billion followers and the rest of the world.
His popular touch, leadership on issues such as paedophile priests and signals of a more compassionate and pragmatic approach to the vexed questions of homosexuality and divorce have removed the sense of crisis that had taken hold under his predecessor Benedict XVI.
But as the erstwhile Jorge Bergoglio prepares to celebrate on Friday the second anniversary of his election, he will be keenly aware that a crunch is looming over the question of how to reconcile Catholic thinking on the family with the realities of how many believers live their lives in the early 21st century.
The Argentine pontiff set the bar high on the issue by scheduling two major synods - gatherings of bishops - on the theme of the family early in his term.
The risks involved were underlined when the first one, in October, saw riled conservative bishops mobilize to block the approval of language heralding an unprecedented opening to the gay community and greater flexibility on the treatment of divorced Catholics.
The outcome was seen as a setback for Francis at the hands of a body in which conservatives continue to hold the whip hand ahead of the second synod this October.
A worried Pope
"What the synod confirmed is that there is now an open conflict within the Vatican over very serious questions," said Marco Politi, a Vatican expert who has recently published an essay entitled "Francis among the wolves."
"The Pope himself is worried," Politi told AFP. "Before Christmas he told a Latin American friend 'the only thing I ask of the Lord is that the changes for which I am making so many personal sacrifices will not be like a light that goes out.'"
Politi believes the historic decision of Benedict to retire rather than die in office - and 78-year-old Francis's own hints he could do likewise - have been game-changers inside the Holy See.
"This is a pontificate with a limited timeframe," he said. "That means opponents can watch the clock and tell themselves, 'we only have to wait four, five years and it will be over.'
"That's new and it strengthens them."
Francis has also encountered subtle opposition to his bid to reform the Curia, the Vatican bureaucracy that runs the Church worldwide.
Publicly, resistance has been muted, but with long-established ways of doing things under threat, "changing mentalities is not so easy," says an inside source.
Francis's occasional characterization of some Vatican officials as pampered and detached - suffering from "spiritual Alzheimer's" as he put it in one cutting phrase - has not won him friends inside the city state.
A tendency to shoot from the hip has also caused concern, even irritation, that major theological questions are being reduced to soundbites.
With his "Who I am to judge" comment about gays, Francis pulled the rug from under centuries of Church teaching that homosexual acts are sinful.
Quips such as Catholics don't need to breed "like rabbits" and the suggestion that those who insult religion should expect "a punch on the nose," have also contributed to a papal paradox: the more popular Francis becomes in the wider world, the less sure is his support in the ranks of the Church.
"Many practising Catholics are uneasy," said Vatican Radio's Romilda Ferrauto. "They understand the Pope's wish to show mercy to those whom life has hurt but they also ask 'what about truth, what about God's law?'"
And it is not just journalists who are prepared to express reservations. "No synod, no bishop, not even a Pope can take away the treasure that is the Catholic faith," one bishop, Athanasius Schneider, recently observed.
Such discordant voices matter, says Politi. "Criticism quickly translates into enormous inertia," he said.
"When the Pope suggests a change in the pastoral approach on questions of sexual morality, the response is a deafening silence. When he demands that servants of the Church live modestly, as he does, you do not see many bishops giving up their palaces."