concerning the existence of a god: it's not up to me to prove the negative that a basketball is orbiting Pluto. It's a crazy claim in the first place (it's not a natural object and there's no way it could have gotten there, at least until recently) and it's not possible to prove the negative. But there is good reason to assume the negative.
Likewise, minds are products of physical brains and millions of years of evolution. Minds live in the natural world and don't have superpowers, like a god. An existing god is a far-fetched low-probability event. No one needs to prove the negative for god. No god is the default.
I assume a conscious mind is natural. A conscious mind only being able to exist once would not be natural, if we judge the conscious mind like other natural events. That's how nature works, at least for those things that can be proven. A conscious mind has some difference than other natural processes that behave like they are natural - that is, events that happen with repeatable patterns. But from everything we know about nature, if consciousness is natural, then consciousness needs to act like it's natural and not have limits on how many times it can appear.
Just like the low to zero probability event where all of existence starts with a god, it is a zero probability event for my conscious-self to exist now in all of infinite time if I only got one life. It takes a lot of faith to believe, or even think reasonable, either of these versions of reality.