Morality is not an instinct
One of the common motifs we find in this book is the idea that morality is not an instinct but rather a characteristic that can be found only in humans. Lewis argues that if morality would be an instinct, our first reaction when we would hear someone cry for help would be to run the other way to save ourselves. However, morality tells us to go and help the person in danger so because of it we sometimes do not act in our best interest.
The need for philosophy and religion
Another common motif in the book is the idea that humanity needs both religion and philosophy to survive and to live a happy life. According to Lewis, science can explain how the world works but cannot answer a couple of important questions posed by humanity such as why we exist and why we behave the way we do. These questions can only be answered by religion and by philosophy and thus we need them in our lives.
We can’t be happy without the presence of God
Another common motif found in the book is the idea that humankind cannot be happy on its own. Lewis points out that humanity tried time and time again to be happy without God’s help but that every attempt failed for one reason or another. This represents for Lewis proof that humans were not meant to find happiness without God’s help and that trying to find happiness outside religion is foolishness.
Christ works through you
Another common motif found in the second book is the idea that Christ operates through those who believe in him. Through them, Jesus is present into the world because those people engage knowingly in actions that they know will copy the type of lifestyle Jesus had while he was on earth.
Sins
Another common motif in the book is the idea that sins, while they provide happiness and pleasure to those engaging in them, can stop humans from achieving the salvation offered by religion. Lewis argues that while those who sin feel pleasure and feel good soon after sinning, they usually fell guilty after that and they also jeopardize their chances of being saved.
