Edward Boyd's agnosticism rested "not ... too much on any positive position ... but rather on a host of negative ones" about Christianity. In an attempt to address these negative issues, his son Greg, a professor of theology, asked his father, a strong-willed, highly intelligent, and stubborn 70-year-old, to enter into a correspondence in which "all of their cards would be laid on the table." Greg would give his father the opportunity to raise all his objections to the veracity of Christianity, and Greg would "answer these objections as well as give positive grounds for holding to the Christian faith." Three years and more than 30 letters later, Letters from a Skeptic was published and Edward Boyd came to accept Christ. During his journey, he and his son hash through such topics as why the world is so full of suffering; why an all-powerful God needs prayer; how you can believe in someone who rose from the dead; and how another man's death can pardon others. Despite their brutal honesty, both men exhibit respect and love toward one another as they address these volatile subjects.

We have to be continually reminded of what we believe. Neither this belief nor any other will automatically remain alive in the mind. It must be fed. And as a matter of fact, if you examined a hundred people who had lost their faith in Christianity, I wonder how many of them would turn out to have been reasoned out of it by honest argument? Do not most people simply drift away?

I am not asking anyone to accept Christianity if his best reasoning tells him that the weight of the evidence is against it. That is not the point at which Faith comes in. But supposing a man's reason once decides that the weight of the evidence is for it. I can tell that man what is going to happen to him in the next few weeks. There will come a moment when there is bad news, or he is in trouble, or is living among a lot of other people who do not believe it, and all at once his emotions will rise up and carry out a sort of blitz on his belief... Now Faith, in the sense in which I am here using the word, is the art of holding on to things your reason has once accepted, in spite of your changing moods. For moods will change, whatever view your reason takes. I know that by experience. Now that I am a Christian I do have moods in which the whole thing looks very improbable: but when I was an atheist I had moods in which Christianity looked terribly probable.