No, you scientifically illiterate jackwad! It is a scientific theory (actually, two, but who's counting) that has been repeatedly tested for about a century or more, depending upon which one of his *two* relativity theories (yes, now, we are counting) we are talking about. And not a single repeatable, soundly-conducted experiment has disproved either one. And that mountain range of evidence is why the scientific community accepts Einstein's theory of relativity.
Unfortunately, much of the non-scientific public, yourself obviously included, doesn't understand the difference between the everyday use of the word "theory" versus its meaning in science. So, here is a handy article that discusses the matter. Read it. Comprehend it. Absorb it into your consciousness. And then check back with the grown ups.
http://undsci.berkeley.edu/article/howscienceworks_19