What does 'miss heaven by 12 inches' mean?
The expression means a person can mentally acknowledge the gospel yet never truly believe it in the heart. The twelve inches pictures the distance from head to heart: many have head knowledge only, giving mental assent without heart faith, so they miss heaven. True belief is heart trust, not just intellectual agreement.
Les explains that when he speaks of believing, trusting, and having faith in the gospel, he means a true heart belief, not just a head knowledge. The expression says many people will miss heaven by 12 inches because they had it in the head but never got it in the heart. He stresses that we must be sure we are believing, not merely giving mental assent, but trusting our whole eternal destiny on it. He adds that there is an eternal doom coming for those who do not have that kind of heart faith, so this is a serious matter.