Because science is fact, it is demonstrable and repeatable but none of those religions are fact, and there are all just stories based on no facts or evidence at all.
Because only science is known for sure to exist, and facets of religions that ate known for sure to exist, such as being able to influence things through though, are also science.
They teach the histories of those faiths, where they are found in the world and how they have affected human history, but they don't teach the dogma, as we live in a society that has a separation between Church and state. Want to learn about fairy tales? There is time for that on the weekend.
Because you can prove science with tangible evidence that the majority of the civilized world accepts as true. It isn't controversial, and it is useful for students who want to do something with their lives other than trolling on Yahoo Answers.
Science is "supposed" to deal with things which are testable. The problem is that there have been numerous "theories" which have not been pr oven accurate, but have been taught, nevertheless, as truth. If they are going to preach on their theories, then they should at least look at all the available points of view. A good judge weighs all the facts. A bad judge just picks and chooses something as the truth. They should just be honest about evolution, simply being a theory and allow people to work off of the information that they are given and research for themselves. There is a lot of legitimate evidence for the Bible. In attempts to disprove the Bible, people like Lee Strobel, many archaeologists, and other people have actually found more evidence supporting it.
You are of course incorrect. The scientific method is taught as a way to get at and understand facts. Some things are fact and have stood the test of time. Other things are theories and are still being worked on. How is it that you are confused? What is it specifically that you regard as real in Christianity, Catholicism, or any of the others? Lets set up an experiment and find out if there is anything at all in all of that which we can call a "fact." Just pick something and we will test it. That should be simple enough to do. I am fairly certain that if we can prove any of these to be factual, we can get them into a school curriculum tomorrow. Frankly speaking; they would also be on the international news in a heartbeat. So, what is it that you want to test? I'm ready willing and able to give you a hand.