Pope Francis has the distinction of being one of three leaders—alongside Amazon CEO Jeff Bezos and Apple CEO Tim Cook—who have made Fortune’s list every year of its existence. This past year has been the year of Pope Francis the diplomat. The first Latin American pope played a key role in brokering a deal between the U.S. and Cuba, writing letters to both presidents Barack Obama and Raul Castro encouraging the two nations to find common ground. For the first time ever, Francis traveled to the U.S., to deliver his message of social justice in the world’s most powerful country. Francis dug particularly sharply into what he called the “dung of the devil,” criticizing “the idolatry of money and the dictatorship of an impersonal economy lacking a truly human purpose.” And his Laudato si’ encyclical calling for “swift and unified global action” in defense of the environment undoubtedly gave momentum to the effort that led to a global climate change pact in Paris in December.
The pope’s unapologetic advocacy on behalf of the poor and the environment has only boosted his popularity—when he launched an Instagram account in March, he gained 1 million followers in 24 hours. But the tension between the Catholic Church’s culturally conservative adherents and its more socially progressive followers remains among Francis’s trickiest managerial challenges. He continues to thread a tight needle, making the church more welcoming to LGBT worshippers and divorced Catholics while assuring traditionalists that he isn’t changing doctrine.