The Conquest of Fear is written as personal testimony rather than a thesis. King begins by admitting that for most of his conscious life he was a prey to fears, and he takes it for granted that he speaks for the majority. He looks around and sees the mother afraid for her children, the worker afraid of his competitor, the clerk afraid for his job, and concludes that fear, more than sin or sickness, is the steady drain on human happiness.
His turning point came in a dark hour at Versailles, ill, alone, and losing his sight, when a seed planted in boyhood finally germinated. A teacher had once spoken of the ingenuity of the life-principle, the force that came to the earth and adapted itself to every new condition, seeking the land when pursued in water and the air when pursued on land. King drew the conclusion that this force carries a conquest-principle with it, and that as individuals we need difficulties to overcome, with fear acting as the stimulus that calls our energies into play.
From the life-principle King moves to God. He found his inherited picture of God too small and remote to help him, a figure kept in a labelled compartment and brought out only for services. He set out to find God for himself, plainly and freely, as the near source of life rather than a distant judge. He grants that God in His being is unknowable, but argues that we may infer His goodness, love, and power from what He does, much as we know the life-principle only from its works.
King then applies this trust to the particular fears. He treats sickness and poverty as trials we largely bring on ourselves by closing the channels through which abundance would flow. Each person, he argues, is unique and of first value to God, so restriction is not God's will. The fear of death he answers with the principle of everlasting growth: life is a continual climb, and the deadly tendency in us is the closing, contracting mind that begins to die before its time.
The book ends where it began, in personal restraint. King condenses his whole experience into four words, calmly resting and quiet trust, and admits that trying is as far as he has gone. He claims no recipe and seeks no converts. The closing note is that as each generation perceives more of the underlying power, it is freed a little further from fear and feels its abundance of life more strongly.