Well, at best, religion is based on an indemonstrable premise. It is, obviously, a matter of choice, a matter of belief or faith, if you will. Therefore they may or may not be valid for everyone. If anyone refuses to accept the premise of religion, the whole moral system crumbles.
However, philosophical theories that deal with moral issues, specifically those that address the "moral minimums" are somewhat solider in that they stem from formal reasoning. It's not so easy to dismiss them, unless you want to assume a relativist stance. We could do that, and I reckon it's a valid approach, but it's not a very efficient or fruitful one, as I'm sure you will agree.