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

[Belacqua]

To me, religion is the result of the corruption of something that originated from science, and the reason it happens is because there are greedy people who want wealth, power, and control (or already have it and want more), and will lie, cheat, and steal to get it. It's something that I think has been happening ever since the dawn of mankind (a couple million years ago), it has been happening ever since, is happening today, and will continue to happen in the foreseeable future.

I'm curious about this... What is the science which existed prior to religion? Do you have some examples? In what way was it corrupted to become religion? 

The word "science" in its modern sense started in the 18th century. Before that when people investigated the world it was called natural philosophy. The separation of what we call science from what we call philosophy is quite recent. And philosophy was largely integrated with religion for most of that time.

Some branches of science got started in practices that were intrinsically involved in religion. For example, the desire for improved astrology motivated astronomy. (Remember that Kepler served as court astrologer for the Holy Roman Empire.) Alchemy was founded on various Neoplatonic beliefs that we would call religious today, but which gave rise to modern chemistry eventually, after much weeding and sorting. (See the history of Paracelsus.) 

So I don't understand why you put science first, as if it had a pure uncorrupted state before religion came in.