can stories from a religious text-the Bible, the Koran, the sayings of Confucius-be treated as myths?
Of course such stories can be treated as myths. Many stories, at least from the Christian Bible, can easily be seen as myths rather than as factual descriptions of what actually happened. For example, in the creation story in Genesis, God only created the sun and the moon on the fourth day of creation. This seems to contradict the idea that this is a factual account. Similarly, Genesis claims that there was a flood that covered the whole Earth. There is no widely accepted evidence that this happened. In the New Testament, for example, there is the story of Jesus sending demons out of a man and into a herd of pigs. All of these are stories that are not scientifically supported. Any story that is not supported by science can be seen as a myth.
