1. Every natural, innate desire in us corresponds to some real object that can satisfy that desire.
2. But there exists in us a desire which nothing in time, nothing on earth, no creature can satisfy.
3. Therefore there must exist something more than time, earth and creatures, which can satisfy this desire.4. This something is what people call "God" and "life with God forever."
C. S. Lewis, who used this argument often, summarizes it with these words: "Creatures are not born with desires unless satisfaction for these desires exists. A baby feels hunger; well, there is such a thing as food. A duckling wants to swim; well, there is such a thing as water. Men feel sexual desire; well, there is such a thing as sex. If I find in myself a desire which no experience in this world can satisfy, the most probable explanation is that I was made for another world." (Mere Christianity, Bk. III, chapter 10, "Hope")