What does Sam Harris mean by saying that religions are failed sciences?

[Anomalocaris]

I don't see how can somebody think that religions are somehow failed sciences. Religions were not trying to follow the scientific method and failed at it, they were doing the opposite of the scientific method from the beginning. A failed science is perhaps n-rays or stuff like that, certainly not Christianity and Islam.

i think he used the word poorly.   religions are failed, and mostly disingenuous, efforts to make sense of reality in ways that can be validated and are persistently useful, while science are much more sincere and rather more successful efforts at the same thing. 

The chasm in their motivation and performance highlights the fact that one is not the equivalent of the other.