I think it says a lot about someone if they do litter. To be clear I've not always been perfect and as a smoker I had no doubt just stubbed some cig / joint ends and just ditched em, now I know how bad for the environment that is I wouldn't do the same now. But yeah the littering thing is just being inconsiderate of the world around you, I guess if you live somewhere that is already a brick hole people don't see the point of taking care of that place but that isn't an excuse.
On religion, for me seeing how strong other people's faith is in other religions / deities would make me doubt mine. I guess before multiculturalism you'd only see / meet people that followed the same religion as you but it wouldn't come up.
The chances of one of the organized religions being right is low, but we can't even necessarily to prove that this isn't a matrix style simulation. If there is a GHod that created everything, it's fairly arrogant to think that just because we can't find evidence, means that there isn't (or wasn't) a GHod. I'm firmly on the fence but there is a fudge tonne we don't understand and the point of science is that it is there to be tested - What's understood as fact will most likely be miles off how we see things in a couple of centuries.
Nothing comes from nothing, but it must have done, unless there's always been something but the big bang suggests otherwise, but that's only our best theory. It's a paradox that hurts to think about.