VATICAN CITY — The American archbishop who welcomed Pope Francis to the final rally of his U.S. tour warned Friday that Francis’ big family summit of bishops risks doing serious harm to the Catholic faith if it endorses changes to the church’s practice on marriage.

Archbishop Charles Chaput of Philadelphia took to The Wall Street Journal to convey the “anxiety” and “worry” felt by many bishops over proposals at Francis’ three-week synod on the family to change the church’s practices of ministering to divorced and civilly remarried couples. Chaput, who hosted Francis in Philadelphia earlier this month at a big family rally, warned that a change in pastoral practice could eventually lead to a change in what Catholics actually profess.

“Practice inevitably shapes belief,” he warned.

Chaput’s alarm underscored the core tension running through the closed-door meeting that has laid bare the split in the Catholic Church between conservatives who insist that restating church doctrine is the best answer to families in crisis, and progressives who want to treat family problems with a more accommodating, case-by-case pastoral practice.

The tensions came to a head this week with revelations that 13 cardinals – headed by Australia’s George Pell and including New York’s archbishop, Cardinal Timothy Dolan – penned a letter to Francis expressing grave concerns about the way the synod was being run and warning that Rome could go the way of “collapsed” Protestant churches that abandoned core Christian beliefs in the name of pastoral “adaptation.”

The synod enters its homestretch this coming week, when the 270 bishops will vote on a final document that will be given to Francis. He has not said if he will publish it immediately.