Take someone soul?

You actually can, I know what I'm talking about. But whatever...

Something to make note of, that is more of a personal opinion, really. The belief or disbelief in the Devil (or any higher being, entity, etc) is a personal one. So, just because you believe in it (or the other things that you've stated here) does not mean that others feel the same or even see it in the same light.

only the devil can take souls

Why would there be any meaning for takìng someone's soul, it could be playing with the Darkest of Magicks

This is why I focus on white magic