Any disagreements people have about Religion aside it is unarguably a influence on people's culture and personality.

So quite simply it would simply be an RP injustice to try to avoid or not address it with your characters.

(What? No long rant on Religion? Are you ok Gwazi?)
I'm fine, this is just a pretty clear cut case in my opinion. If something plays an effect on people it's something that RP's should at the very least address.