Obviously this is a never-ending issue. However, there are some questions that can put your theory "everything has always been here and always will" in major difficulty. Any system is not perfectly stable, included our own Solar System or the Earth-Moon system for us or any planet. So surely, any system must come from a previous parent system. (eg. Supernova -> Solar System) So what came before our current system? and before that? and before that? At some point, it all has to start with a Big Bang or some sort of catastrophic event that can also explain the redshift observed in the wavelength emitted by galaxies. Also if you say that the Universe has always been here, this almost surely includes the fact that the Universe's size is fixed. If not, surely there has to be a beginning. And obviously the WMAP data from supernovae clearly show the rate of expansion of the Universe is accelerating. I fear your theory comes solely from the grandness of the problem and the lack of accessible proofs in everyday life. But I'm sure that if you would start reading some papers around the web, you'd change your mind pretty quickly.