Complex sentence: In 1946, McCall became Executive Secretary-Treasurer of the SBC Executive Committee, the Southern Baptist Convention's central coordinating body, leading it during a time of growth that eventually saw the SBC become the largest Protestant faith group in the United States.
Split into simpler sentences: In 1946, McCall became Executive Secretary-Treasurer of the SBC Executive Committee, the Southern Baptist Convention's central coordinating body. During his tenure the SBC become the largest Protestant faith group in the United States.