C.S. Lewis, in his book "Mere Christianity," emphasizes the importance of intellectual engagement in spiritual growth, comparing spiritual sloth to other forms of laziness. He argues that a lack of intellectual effort is not viewed favorably by God, suggesting that believers should actively seek to understand their faith and embrace critical thinking. This underscores the idea that faith is not simply a matter of blind belief but involves a commitment to reason and understanding.

Lewis highlights that God expects more from individuals than complacency; being spiritually stagnant is akin to being lazy in any other aspect of life. He encourages readers to cultivate their minds and harness their intellectual abilities as a way of honoring God. True faith integrates both heart and mind, and intellectual engagement is a key component of a vibrant spiritual life.