Haarsma might respond that we can see this was a true revelation because it corrects ancient theology in teaching a monotheistic religion of a creator God that was new. But if we're going to read the Bible within its cultural setting, as she does, then we might notice that parts of the Bible seem to accept the polytheistic idea that different peoples have different gods (for example Judges 11:24). We might then wonder whether Yahweh was originally one of many gods who at some point was elevated to be the one universal and transcendent god of Israel, which is the argument of Thomas Romer in The Invention of God (Harvard, 2015). So why isn't God a cultural invention? To deny this, it would help to have a revelation in the Bible of cosmological truths that correct traditional cosmologies in ways that people of the ancient Near East could not have understood, but which might be confirmed by modern science.
The response of the biblical creationist is that it is very unlikely that the Universe would exist uncaused, and it is more likely that God would exist as the uncaused cause of everything.
In our search for ultimate explanations, we must appeal either to nature or to God as the unexplained ground of all explanation. Thus does the natural desire to understand leads us to this most fundamental of choices--nature or God, reason or revelation. Philosophy cannot refute revelation, and theology cannot refute philosophy, because any attempted refutation would have to beg the question at issue. As Leo Strauss observed: "All alleged refutations of revelation presuppose unbelief in revelation, and all alleged refutations of philosophy presuppose already faith in revelation. There seems to be no ground common to both, and therefore superior to both."