No, it is not. To be an athiest has nothing to do with religious inclination, it has to do with lack of belief in god(s). It's right there in the word: a-: lack of; -theist: one who believes in a deity. A Buddhist in the vein of the Buddha, who did not believe in god(s), is an atheist.
Most of the definitions I've found define religion as in terms like 'belief in a supernatural power', or 'worship of gods or similar higher powers'.
Buddhism is not involved with either. I see it really as little different to going to the gym. Do the correct practices consistently and see results. No magic, no worship, no blind beliefs, just steadily progressing and seeing results...
This is as idiotic as:
Are you vegetarian? Yes! Do you eat meat? Yes!