A Look at Southern Baptists in the U.S. Today The annual Southern Baptist convention begins Sunday in Nashville, an event predicted to bring together over 12,000 messengers from churches all over the nation to pray, vote on leadership, and debate theology and policies. This is a significant event, given that the Southern Baptist denomination remains the largest Protestant group in the U.S. and the second-largest religious group in America, behind only Roman Catholics. The denomination -- a fairly loose confederation of autonomous congregations without a strict or official hierarchy -- includes an estimated 47,000 churches in the U.S. Who Are the Southern Baptists?