Why does the Misfit kill the Grandmother when she does the right thing? What statement about faith does this make?
At the end of Flannery O'Conner's, "A Good Man is Hard to Find," the grandmother realizes her responsibility for every human, including the Misfit. She reaches out to him in a moment of clarity, stating he is one of her children. It is at this moment the Misfit kills her. Why is it he kills her when she does the right thing, and what statement about faith does this make?
The key to this question is that first of all, it hasn't been established that the grandmother does the right thing at the end of the story. That is a highly debatable point. Consider the following line, which is found just before she reaches out to the Misfit:
" "Maybe He didn't raise the dead," the old lady mumbled, not knowing what she was saying and feeling so dizzy that she sank down in the ditch with her legs twisted under her."
O'Connor says that the older woman doesn't really know what she is saying, and that she feels dizzy. She even recants part of her supposed faith at that moment, challenging one of the miracles Jesus is said to have done. Therefore, one could say—and I would say—that the grandmother doesn't do the right thing. She just flails around, trying to save her own life. Her faith is false.
However, if you think she does the right thing, and really means those final lines, you could argue that O'Connor is showing that faith and reward in this world have nothing to do with one another.