It's OK not being serious when talking about religion, since religion itself is not a serious matter.
you could post theories for morality. But in the end they are all just theories...
Was that a serious post, or did you just want to be funny?
My guess is you're serious and I'm going to reply in line to that.
A theory is not defined as "something that might just be", it's a conclusion you've come up with after analysis, measurements, logic, etc., etc. A theory is, scientificly speaking, something you use to make something trustworthy, and thus not the opposit. Discarding something because it's based on theories is really one of the worst case scenarios you may experience.
Look here for further reading
http://en.wikipedia.org/wiki/Theory .
For me, there's no hell nor heaven. When you die you just stop function and that's end of story.
Why does life have to be fair?
Why are you so afraid of not existing? Not existing must be the coolest way to "be", since you don't exist.