By Mark Abrams

PHILADELPHIA (CBS) — Pope Francis comes to Philadelphia for a two-day visit at the end of September.

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Now a veteran international journalist who covers the papacy is enjoying success with his new book, The Francis Miracle, chronicling the impact of the election of Francis.

John Allen, associate editor at the Boston Globe and for the newspaper’s online publication about church news called “Crux,” says the fundamental move Pope Francis made shortly after his election more than two years ago was to change the public narrative about the Catholic Church.

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And, Allen says, he has built on that success.

“The dominant story lines about the church in the global media were child sexual abuse scandals and crackdowns on nuns, and bruising political controversies and a Vatican in meltdown. And while those stories have certainly not gone away, it is not the dominant story line any longer. Instead, for two years it has been ‘Rock star pope takes the world by storm.’ ”

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In his book, Allen also talks about the internal struggles between conservatives and liberals within the church while a moderate Pope Francis tries to lead both factions and direct them to a new mission – that of mercy.