Winik uses this allusion to emphasize that, although Booth sounds as though he is very self-assured, and does not seem to regret what he has done, he ultimately admits to being alone and cursed, as though it was his destiny to do what he did. It seems that Winik believes that his being lonely and feeling wronged is a more accurate reflection of Booth than his otherwise self-confidant demeanor gives on.
This allusion (in Booth's diary) is also an important factor, in that it indicates that Booth believed his actions were God's will.
