If you limit yourself only “naturalistic” explanations, then you are now committed to either random chance or some sort of evolutionary scheme (which can include random chance).
There are many “naturalistic” options available for evolutionists to “select” from. ReMine called this ‘Natural’ selection.
For example:
-Separate Ancestry (multiple biogenesis)
-Common Ancestry
-Lateral Transposition (can move a character across lineages)
-Convergence (The independent evolution of similar traits)
-Loss of Character
And many more!
-So let’s say cytochrome c was “identical” in all species. Evolutionists could “select” either Common Ancestry or Lateral Transposition “explain” the pattern. (They would then tell us that if it was created by a creator that it “should be random”, and use the odds against random chance as evidence for evolution. See my earlier posts on this thread).
-Let’s say instead that cytochrome c was “random” across all species. Evolutionists would have no problem. They would simply say it was randomized by mutations. (They would then say (as some already do that if it were created it “should be identical.”)
-Let’s say that human cytochrome c was identical to yeast and that chimp cytochrome c was identical to a lizzard. Evolutionists would attribute it to Lateral Transposition.
That evolutionists are willing to invoke such “explanations” is documented from their own writings (see the afore mentioned book).
Keep in mind that the evolutionists commitment to “naturalistic explanations” is a total commitment. So for them it’s just a process of finding the most plausible (least unlikely) naturalistic “explanation” that they can come up with, no matter how unlikely.