Parallel - pg. 137 "Okay. This is what the good guys do. They keep trying. They don't give up."
A repetition of the moral boost the man has to constantly give to his son.
Contrast - pg. 154 "Some part of him always wished it to be over."
Its a contrast to how he acts towards his son. He keeps telling his son to persevere and keep going for both of their survival, even though he himself doubts their chances.
1. Who is "they" that the father is talking about on pg. 148?
2. Bottom of 154 to 155, could that mean the whole concept of god, is an alien one, as he considers himself an alien to his son, but he himself is a Christian?