Superstition

One of the reoccurring motifs I've noticed in the gunslinger is his constant belief is superstition. It can be seen when 'bones' make a prophesy, when he avoids certain grass in the desert, when he performs a ritual and uses drugs to see another prophesy. I believe that the ending to the novel actually is King's way of saying "superstition is a bunch of bullshit".
“The man in black slipped his hood back. The gunslinger looked at him silently. In a way, the face that the hood had hidden was an uneasy disappointment. It was handsome and regular, with none of the marks and twists which indicate a man who has been through awesome times and has been privy to great secrets.” (King 211)

This quote is the conclusion to the novel. The man in black, whom the gunslinger has been hunting since the openings of the novel, is finally found and confronted. Only there is one problem; he is merely a man. Him and the gunslinger are equals, and there is nothing special about the man in black. The gunslinger was hunting the supernatural, and it turns out to be a fake. King could be pointing out something about life in this case; the possibility that there are always answers to life, there is no supernatural, and superstition is unreasonable.