A scientist would never say that. There are too many questions that science can't answer. Science is not in the business of shutting out possibilities. Science is in the business of finding things out. In science, the lack of an answer is not considered an answer. In science the lack of any scientific evidence of a god doesn't answer the question of whether or not there is a god, so the question remains an open one. Anyone who decides that the lack of an answer is itself the answer and who, on that basis concludes that there is no god, is practicing belief.

It's also not accurate to say that there are mountains of data on the other side. There is no data that says there is no god. There is not even any data that suggests that there probably is no god.

Personally, I am not suggesting that any belief is rational, not belief in a god, nor the belief that there is no god. Belief is, by definition, not rational. It is belief. Neither side of the issue is any more rational than the other. They are both equally guilty of engaging in belief in the absence of proof, and neither is any more rational than the other.