I think Buffy is right, that there isn't a 'science' that you can abstract from what scientists actually do. As the philosopher of science Bruno Latour has argued, science isn't about ideas but about practices - 'science' is the sum total of all the different practices (the doing of science) by all the people involved in it (scientists).
And, of course, all those practices are compromised in particular ways - by funding, by influences and biases and starting points, by chance, by power structures within the institution, by guesswork and happenstance, fashion ... so that, as Buffy says, science is a powerful language for describing the material world that we live in, but not a pure source of truth.
And, of course, there is much that science is not competent to tell us about. It is incompetent when it comes to history, to metaphysics (questions about what existence is, for example), to ethics and to aesthetics. And most scientists cheerfully accept this.
Thinking that science can tell us everything that is worth knowing is Positivism.
So, Bertrand, what I'm saying is that there isn't a thing called 'atheism' that is different from what atheists believe. Your definition is a reductive one, in that it reduces atheism to its most minimal possible level. Other ideas about atheism are possible - Nietszche for instance said not that he didn't believe in God but that God is dead. That's a rather different thing. But I don't think there's much to be gained by a discussion that simply goes round and round. If you want to hold to your definition, that's fine.
Hermione, I've tried to explain above why I think you are idealising science. Regarding your claims about religion, in brief: a) people have very good grounds for believing in God, and their belief is based on evidence. Whether you accept testimony and experience as valid kinds of evidence depends upon your theory of knowledge, of course, but testimony and experience are certainly valid kinds of evidence in a court of law. b) to say that belief in God continues blindly is to ignore the central place that debate and doubt have in the history of religious thought. Did you know, for example, Rabbis are trained by having to argue their ideas out point by point? c) science is almost unique as a form of knowledge in that it regards history as the history of error, and sees only current knowlege as true. No other way of knowing the world has so little regard for the past. Of course religious ideas and practices have changed over the millennia of human existence; but a key feature of religious thinking is that some things are always true - for example the way God has revealed herself/himself. The essential truths are timeless but the interpretation of them is a matter for each age.