In "Mere Christianity," C.S. Lewis defines faith as the ability to cling to beliefs even when one's emotions fluctuate. He emphasizes that true faith requires a commitment to convictions that have been rationally accepted, regardless of how one's feelings may change over time. This establishes faith as a conscious choice rather than merely an emotional response.

Lewis suggests that maintaining faith involves discipline and perseverance. It means staying grounded in one's beliefs, even during difficult periods when doubts or uncertainties arise. Ultimately, he portrays faith as a profound strength that can guide individuals through life's unpredictable emotional landscape.