Let me explain then. If there was an ancient tablet found with the words "God is dead" on it. Would we take that at face value? No, it doesn't have any evidence to support it, there is no reason to engage in debate.

However if you suppose the tablet is correct, you would have to support that affirmation with additional supporting information. The statement of the tablet isn't self evident, so it not really a serious claim. You are making it a serious claim by supporting it, and thus must be the one to provide evidence for that claim.

This is pretty basic debate, which is usually structured into the form of affirmation vs negation. The side of the affirmation is the one making a claim( god is dead), the side of the negation responds by denying the claim and responding to supporting evidence by proposing counter arguments.

It doesn't matter that you didn't make the original claims, only that you choose the side of the affirmation.