[I posted this to Pharyngula just now...]
I sometimes find it helpful in dealing with [theist] nutters [who go on about "spirituality" and such things] to point out that there are two categories of Things-We-Do-Not-Know. These are UNKNOWNS and MYSTERIES. (Apologies for the capitalisation; I'll be trying to work these into acronyms at some point!)
I define the former as things that are in principle knowable, and hence they are not-yet-knowns. Even when they can't in *practice* be known, they are nonetheless non-mysterious.
MYSTERIES, OTOH, are things that we can never know *in principle*. They are beyond mere human ken. They are the realm of the pixies.
The problem for pixie-huggers is that there aren't any situations that fit into the latter category. They *claim* that there are, but there aren't. They will, furthermore, claim that certain UNKNOWNS are in fact MYSTERIES, but that is a leap that imposes upon them a burden of proof, and they are unwilling to be so gracious as to provide that.
So even your first mitotic division sits comfortably in UNKNOWN territory, but it sure ain't no MYSTERY. The vast tree of science is peppered with UNKNOWNS, but these are generally treatable as "black boxes", where we can establish the inputs and outputs of the system, even if we don't know the full details of the inner workings. But pixies cannot live in such black boxes, because these nasty old scientists have a habit of opening the lids and exposing the insides.
November 2016 - I and my pals cycled in The Galilee, Northern Israel, to raise money for Nazareth Hospital Paediatric Department. We raised over £50,000 but we could use more! Nazareth is the largest Arab town in Israel; the people are lovely, and the kids are awesome. Nazareth also treats kids in the West Bank of Palestine who have very limited access to healthcare. They need your help! Go to my sponsorship page to find out more and see what you can do! Maybe even join us in 2017..?