Quotes

Then he just sat there holding the binoculars and watchingthe ashen daylight congeal over the land. He knew only that the child was his warrant. He said : If he is not the word of God God never spoke (page 5)

This quote seems to ive off an important hint about the relationship between the man and the boy. Besides, this 3 sentences reveals the man's characteristic intensively. Through out the whole story, the man seems to be very cold-headed and penetrating. Binoculars he carry all the time shows that he is very prudent. The time set on this scene even emphasizes his cod characteristic. Daylight congeals over the land instead of giving warmth or brightening to the land, 'the man's ' gaze is even more frigid.
Besides the characteristic of 'the man', relationship between the boy and the man is quite mysterious. If you look up the word 'warrant' it means an official writren statement that gives sb permission to do something. First interpretation of this sentence is that the man is actually a 'bad guy'. Though the boy calls the man 'Dad', 'warrant' is not the kind of word you use to your son.
If you look at the page 12, there's another dialogue that might be a clue to this sotry.

You forget soem tings, don't you?
Yes. You forget what you want to remember and you remember what you want to forget. (page 12)

By these two parts of the story, I thought that the important memory the boy lost is the rememberance of the man who is rather an enemy than his helper.
The second way of reading this is that the man is the boy's father. Then, the word 'warrant' will mean something more like a importance to his life. To me it seems that the second way of understanding is more appropriate. Way 'the man' cares for 'the boy' is somewhat tender and is in favor.
On page 11 the dialogue(even though you don't quite know who's asking and who's answering... it seems more likely that the man is the one answering) you can be quite sure about the man's sincere love wtoward the boy who is his son. Because in the point of having nothing but the boy beside him, the man thinks the boy as warrant of his life like an oasis in the desert.

Can I ask you something?
Yes. Of course you can.
What would you do if I died?
If you died I would want to die too.
So you could be with me?
Yes. So I could be with you.
Okay. (page 11)

Whichever way you interpret the word 'warrant', the boy is essential for the man's survival. The man, therefore regards the boy as the word of God. He thinks the boy as the last hope.