Complex sentence: Sutherland's parents had left the Latter-day Saints church and become Presbyterians while Sutherland was still a child, and his political career was probably stunted in Utah as a result of his no longer being a Mormon.
Split into simpler sentences: Sutherland's parents left the Latter-day Saints church and become Presbyterians while Sutherland was still a child. His political career was probably stunted in Utah as a result of his no longer being a Mormon.