I think from identifying as an atheist and debating with theists, and now returning to belief, having been on either ''side,'' my advice would be to just simply accept that you both will be coming at the argument, in entirely different ways. You will be seeking material evidence, or some type of objective evidence, whereas the theist/believer will be coming at the argument from the approach, that much of what they believe comes from faith. From believing in things unseen, and unproven. Unproven in a secular way. To many Christians for example, the Bible is a type of proof of their beliefs, but that will never be the case for an atheist...so these debates can be trying for the atheist and theist alike, since they both approach their arguments from different angles.
There are historical accounts of philosophers and scientists who have believed in the existence of a god, but their opinions still wouldn't serve as objective proof. So, the challenge that you both have is to establish what will be considered valid points of reference to debate with, not necessarily what you're debating about.
There are historical accounts of philosophers and scientists who have believed in the existence of a god, but their opinions still wouldn't serve as objective proof. So, the challenge that you both have is to establish what will be considered valid points of reference to debate with, not necessarily what you're debating about.