I don't understand it: Why am I not confietable with the label "Atheist"

[robvalue]

You're welcome

I would say if they pressed you further than that, they are being unreasonable and you're well within your rights to say it's a personal matter. If someone says they aren't interested in football, you don't pin then down and grill them about whether they believe goal posts exist, do you?

Maybe as you get to know people better, you could unpack it a little more. But it's a matter of whether it will be productive. Their original question betrays a closed mind: what religion are you? So personally I'd need to see more evidence that the person can actually handle more detail before going any further.