Science never says the debate is over. It says that there's an explanation that so far fits all the available evidence, or, if there's contrary evidence, we don't have an alternate explanation that explains all of it. Saying that the debate is over is pretty much the opposite of science.
The problem is, in this case, you're talking to people who are used to thinking in terms of absolute truths, and assume that any level of uncertainty means an argument is flawed. So you either speak to them in their own language, or they'll never stop saying "it's just a theory!"
Science never says the debate is over. It says that there's an explanation that so far fits all the available evidence, or, if there's contrary evidence, we don't have an alternate explanation that explains all of it. Saying that the debate is over is pretty much the opposite of science.
The problem is, in this case, you're talking to people who are used to thinking in terms of absolute truths, and assume that any level of uncertainty means an argument is flawed. So you either speak to them in their own language, or they'll never stop saying "it's just a theory!"