Question for Jewish atheists

I just finished listening to an 18forty podcast episode titled “Aliza and Ephraim Bulow: When a Spouse Loses Faith”, and it made me wonder about something. I first want to be make it very clear that although Ephraim Bulow lost his faith, he is NOT an atheist. As he says during the discussion, he calls himself an agnostic. (I don’t want anyone misunderstanding him based off of my question.

For the Jewish atheists here, I’m curious what keeps you identifying as a Jew, if the entire Jewish identity is based on Judaism being a religion given to us by G-d. If, as you believe, G-d doesn’t exist, thus making Judaism a fabricated origin, then what makes you believe that “being Jewish” is actually a real thing? And, I guess, what do you believe is the point in keeping that identity?

(Of course, I’m not asking this out of any hate, nor am I looking at all to pick a fight. I’m just genuinely curious. [I also think it’s actually a good question if I may say so myself.])

Edit: By the way, I highly recommend the podcast episode. I found both Mr. And Mrs. Bulow to be very inspiring and incredible people. I actually first watched Yaakov Langer’s episode with Mrs. Bulow on his Inspiration for the Nation podcast. (I watched it on YouTube, but it’s available on music and podcast apps too.) Such a powerful episode as well. I, for one, found the part when she speaks about her marriage to be the most powerful part in the episode (but the entire talk is really great and inspiring). That part even made me tear up. (Possibly other parts did as well, but I remember tearing up by that one especially.) Their relationship is just unbelievable, and I think really anyone from all walks of life can gain from hearing how loyal they are to each other, and how much they respect one another. Including anyone in any kind of relationship, even just siblings or parent and child.

Edit 2: After starting to read the responses, I feel the need to look into this more (i.e. ask a wiser person than me) about whether we religious Jews believe that G-d gave us Judaism or it’s something we chose. (And if it was through His covenant with Abraham or through giving us the Torah.) For obvious reasons, I’ll refrain from replying to anyone about what I believe vs they/you believe, until I get a clearer picture on what the religious Jews believe based on the Torah.