The sermon explores the concept of certainty and its relationship to doubt and humility, suggesting that declared uncertainty can foster positive traits. The speaker also examines the nature of belief versus knowing, arguing that beliefs are deeply tied to identity and that Unitarian Universalism is less about specific beliefs and more about the practice of how one believes, emphasizing continuous questioning and openness to different perspectives. The sermon advocates for embracing doubt, seeking truth collaboratively, and engaging with differing viewpoints to avoid intellectual isolation and foster spiritual growth and societal transformation. The speaker illustrates the possibility of changing deeply held beliefs through a personal anecdote about his father learning tolerance.