Leathercrop, if we assume that something is eternal --that it has always existed-- then there is no start point. It exists forever into the past. If that seems incomprehensible, that's because it is. At least to us, anyway. I cannot comprehend it. The notion of there never being a starting point simply doesn't compute. And yet, here we are.
So, regardless of what we believe, that situation exists. Otherwise we must assume that either gods or universes can appear out of nowhere, out of nothing, at any time. Could this happen? Hey, one incomprehensible situation is just as good as any other! Of course, that could be tricky... do these gods or universes also poof out of existence spontaneously? Perhaps some of the gods of the past, which we assume to be made up, actually existed for a time! And maybe that's why Yahweh (presumably the most recent one) hasn't made direct contact with humanity for so long?
Of course, I'm just spitballing here. When things get weird enough, we can reach for more outlandish explanations. None of it necessarily gets us closer to the truth, they're just fun thought experiments.