VATICAN CITY, Holy See (AFP) — Pope Francis issued a warning to US bishops on Thursday, saying in a letter that using marketing tricks or flow charts would not restore trust in the Catholic church following the sex abuse crisis.

“Loss of credibility calls for a specific approach, since it cannot be regained by issuing stern decrees or by simply creating new committees or improving flow charts, as if we were in charge of a department of human resources,” Francis wrote.

Attempts to restore the centuries-old institution’s credibility must be based on rebuilding trust, he wrote, rather than “concern with marketing or strategising to reclaim lost prestige or to seek accolades”.

The pontiff also warned against reducing the church’s mission to the administration of an “evangelisation business”.

The US bishops were gathered at a Chicago-area seminary for a prayer summit in advance of a historic gathering that the pope has called for in February at the Vatican, to discuss the ongoing crisis roiling the church.

A litany of child sexual abuse scandals has rocked the Catholic church, which has 1.3 billion followers around the world, with the pope as recently as December accepting the resignation of a US auxiliary bishop over his “misconduct” with a minor.

Francis has struggled to resolve the problem as the steady drip of scandal corrodes the church’s authority amid sharp divisions in Rome over how to handle the fallout.