When you ask if some one is a believer, I have to ask: Believer in what?
Belief is a very big subject. Do I believe in a God? Yes, although I prefer to keep my opinions to myself these days. Do I believe the Earth is flat? No. Do I believe the Watchtower? No. Do I believe in the scientific method? Yes.
So what are we talking about?
JeffT, I can’t speak for everyone, but when I refer to a ‘believer’ I’m referring to a person who believes in the reality of loving, all wise, Creator God. I distinguish between a lover of God and a lover of a religion.