I’d be hard-pressed to find more challenging and complicated questions than how the universe began and how inorganic molecules managed to come alive. There certainly are no shortages of hypotheses and theses for how to explain these phenomena, but clearly, humans don’t have all the answers yet (although most people have no idea how close we really are to understanding these phenomena).
In that sense, Christians and other theists have some justification of putting the burden of proof onto atheists, given that the atheist worldview is absent of supernatural phenomena.
The thing that always struck me as odd, even when I was a Christian, was that those same people, who would gleefully ridicule atheists who reject supernatural intervention, would go on to explain that life’s origins included women being formed from a rib, sneaky snakes, forbidden fruit, and zoo arcs crafted to defend against global, year-long floods.
Humans have only had formalized logic for maybe 2500 years, and it took almost two thousand years more for us to figure out how to estimate the area under a curve in mathematics. Couldn’t it be that, given humans’ fairly primitive current condition, that we just haven’t figured it out yet? Couldn’t it be that, although these problems are profound and complicated, they don’t need supernatural explanations?
The beginning of the universe and abiogenesis are not easy things to grapple with. To attack them with any sort of authority, one needs to understand a huge collection of science that took the most talented and knowledgeable humans on Earth thousands of years to collect and deduce. But if history tells us anything, it is that the best method for humans to unravel the complexities of the universe is science. In other words, our best method to answer very complicated questions is to start with, and assume, natural causes and effects.