BIRMINGHAM, ALA. — Leaders of the Southern Baptist Convention, the largest Protestant denomination in the United States, opened their annual meeting this week vowing to focus on an issue that many pastors have long resisted: how to address sexual abuse at their churches.

Thousands of pastors voted late Tuesday afternoon to address the problem in a concerted way for the first time, enacting two new measures they say are a first step to reform. Outside the arena where they were gathered, victims and their families protested what they considered an inadequate response.

The pastors voted to create a centralized committee that would evaluate allegations against churches accused of mishandling abuse. They also approved an amendment to their constitution that would allow such churches to be expelled from the convention if the allegations were substantiated.

“Protecting God’s children is the mission of the church,” the denomination’s president, J.D. Greear, said on Tuesday morning as he addressed the gathering. “We have to deal with this definitively and decisively.”