What is the theme in Snow by Orhan Pamuk?

Religion is another theme in this book. God played a big part in this book—whether someone believed or didn't believe, and if they didn't believe, what would happen to them. The sheikh, Blue and the religious students were ardent believers, who distrusted anyone else who was not of their religion. The Islamists and the high school boys were religious fanatics who believed only one way was the correct way to live - that of the Koran. They thought that anyone who didn't abide by their beliefs was an atheist.