Complex sentence: Wilensky-Lanford argues that Sadler attempted to avoid placing an individual at the center of his beliefs due to his disappointment in Ellen White, however, Gardner believes that Sadler sought to replace White with Wilfred Kellogg.
Split into simpler sentences: Wilensky-Lanford argues that Sadler attempted to avoid placing an individual at the center of his beliefs owing to his disappointment in Ellen White. However, Gardner believes that Sadler sought to replace White with Wilfred Kellogg.