On a scale of 1-5, how much/little do you care about someone else's religion
5 being a possible reason to never talk to someone again and 1 being something you don't care about at all.
In my case, I'd say 2, since I do disagree with them which can range from being a starting point for a fun conversation or the start of a random preaching spree.
It would depend, not on their religious beliefs, if any, but whether they try to impose them on me / others, their level of arrogance or humility, their kindness or lack thereof. In other words, my malfunctions with people have to do with lack of character / empathy, pretty much separate from their (un)beliefs. Being religious neither makes a person an asshat, or prevents them from being one.
I have met malignant liberal Christians and very kindly and decent fundamentalist Christians. Although the association is usually backwards from that, it doesn't have to be.
The only reason it would concern me is it the tried to influence me with the religion.
I would put myself on a minus 1. It is a matter of complete indifference to me what mythological nonsense others believe in, as long as they don’t try to make me believe it too!