Ok then, just to see without any of my biases, how would you refute someone going on T.V. and saying "all Jews should convert to atheism because what it says about the firmament with lights set in it doesn't exist so the whole book is a lie..."?
The statement doesn't make sense.
The choices are more than Judaism and atheism.
If Judaism were somehow invalidated by that, then the only option would not be atheism. There are at least hundreds of religions that have no Biblical connection at all. The only ones that would be affected by that at all would be "Abrahamic" type faiths (Judaism, Christianity, Islam, Mormonism, etc.). A religion such as, for example, Taoism, would not be invalidated because of anything written in the Bible being scientifically inaccurate. So, it's not logical to say "If not Judaism, then default to atheism".
The second point of interest is to establish whether or not Judaism (and other faiths that have some Biblical connection) would be invalidated by that. It would take an analysis of what exactly the "firmament" was supposed to be and whether or not it really is important as to whether the ancient authors saw the sky as being some kind of trapped water with lights fixed to it on a dome. If they did see it that way, would it invalidate the faith as a whole? Would it invalidate the principles that were being taught in the relevant verses? These are things that are worth researching BEFORE you are faced with this question.