In his book The Moral Landscape, Sam Harris summarizes Francis Collins’ beliefs about the history of the universe: Collins believes in the Big Bang and the expansion of the universe, divine intervention at the origin of life, and an evolutionary process that brought us to human beings. Even though Collins agrees with Harris about the history of the universe before and after the origin of life, Harris only presents Collins’ views to mock them; he simply assumes that his readers, like he himself, will find the idea of a divine origin of life preposterous.
Of course, it wasn’t Harris’ intention in a book about morality to write an argument against the idea of divine intervention at the origin of life (I assume he has done so elsewhere). But his treatment illustrates the fundamental problem with debating about the origin of life: since all we have is speculation, our conclusions will usually rest on assumptions of what’s plausible.
The debate about origins ultimately boils down to making inferences, inferences that depend on other things we believe. If we’re inclined to believe in supernatural powers for other reasons, we’ll be inclined to accept the divine explanation. If we think the idea of God is ludicrous for other reasons, we’ll assume a naturalistic origin. But either way, because we have no solid information, it will be our preconceived notions of what is plausible that determine what we believe about this “black box.”
(To be clear, my argument isn’t, “Humans weren’t present, so we can’t know.” We have plenty of documentary evidence for the Big Bang and subsequent development of the universe, including the evolutionary process here on earth. We can be confident that those things happened. But we have no reliable information about the origin of life, hence, a black box.)
The point is: if you’re arguing in circles about the origin of life with a Christian or an atheist, the reality is that both of your beliefs about the subject depend on other things you believe. Spend your time debating those things instead and stop wasting your breath.