A series of scandals will be looming large in the eyes of church leaders and Vatican watchers alike when a highly anticipated conference on child abuse in the Roman Catholic Church begins on Thursday.

The meeting was called to address decades of abuse disclosures that have rattled the church, eroded trust in its leadership and driven away some of the faithful.

The gathering is intended to be a moment to realign and move forward, and before it began, in what many saw as a significant step, the Vatican expelled Theodore E. McCarrick, a former cardinal and archbishop of Washington, from the priesthood. It was the first time any cardinal has been defrocked for sexual abuse.

But while the church expressed hope that the four-day meeting of 190 participants from across the world, including Pope Francis, would mark a turning point, there is a risk that fresh controversies may overshadow it.