Atheists/agnostics of Lemmy, do you believe in the existence of souls?

It comes down to how you define "soul".

Do I believe there's a consciousness that transcends death or exists separately from our physical existence, no.

But if you start talking of ship of Theseus/transponder incident/mind upload -type mental exercises, then yes, I believe "self" is an evolving pattern and a collection of experiences that could theoretically be replicated in another physical manifestation or even in a completely different medium. You could call that, too, "soul".