Not really, some of the people in this very thread are pretty religious about their atheism.
Using the word religious to describe "passionate" or "determined" does not make it actually religious. I'm a religious Toyota fan, or that's how my friends would describe me, but that's a metaphor or something.
Fundamentally, if you believe in any god, I think that makes you religious. Remember that the word "god" is a made up word. So to believe in the meaning of the word is to believe in the teachings of the people that started the religion. If that isn't true, where would your (not you in particular snowklinger) idea or image of god come from?
Now, if you are atheist, it doesn't mean you're non-religious. I'd argue that I'm mildly religious in so far as I have read several books by the current Dalai Lama and I try to use his teachings to handle daily situations in my life. There are some that suggest that Buddhism isn't a religion in the technical sense though.
So, passionate, determined, hard headed, can all be used to describe both believers and non-believers alike. But it is my interpretation that theist=religious.