When an initial premise has no supporting evidence,

[MineralMan]

10. Why would anyone state that as a premise?

I would say, instead, "No evidence exists showing that any deity or deities exist."

A negative statement requires no proof and cannot be proven. If you have evidence of the existence of a deity, you can simply present it, and my statement will be false.

It is the same as if I said, "There is no such real animal as a unicorn." Unless you can produce evidence of a unicorn, the negative statement is true. However, if you state that Unicorns exist and live in deep dark forests, the burden of demonstrating the truth of your statement is on you. Negative statements have no such burden of proof.

Here's the thing: I would not base a logical argument on a negative premise. If I say there are no deities, nothing about deities follows from that, because no deities exist. There is no substance on which to base a logical argument. If you wish to have an argument about deities, you must first produce evidence of them. Otherwise there is no substance to your argument, either, since you begin with a different premise.