Indeed, that is the reason for these threads, other possibilities exist. One such is that species were intelligently designed by a Creator.
Since neither of these possibilities has been observed one must try to deduce from available evidence which is the more likely of the two. The discovery of DNA has scientifically shown the unlikelihood of mutations being able to achieve the large transformations required for evolution to be true. Intelligent design by a Creator is therefore the most likely of the two possibilities.
That's fine; let's eliminate environmentally random genome mutation as the mechanism of variation. What about molecular automata though? This is actually gaining favor as the most likely source for most of the variation and complexity in living organisms, rather than random environmental mutation. Not only do we observe molecular automata mechanisms active in biology, but it also causes slow and steady genome drift (and growth) in species.
Based on the best knowledge we have today, it would actually seem that automata mechanisms cause the vast majority of variation, with random environmental mutations only playing a secondary role. Natural selection still prunes certain branches of the variation tree, but steady genetic growth and drift seems in fact to be an intrinsic part of our biology. In this sense strict Darwinian evolution (mutation/selection) is probably incorrect, but then most people's understanding of science is frequently 20 years behind the current front-line anyway.
I agree with the anti-Darwinians in the aspect that mutation seems too slow and too irregular to produce constant reliable genetic drift. In theory strict mutation/selection could work (i.e. there is nothing wrong with the basic concept), but by itself the argument seems strained from a probability standpoint. The automata mechanisms don't have this weakness though -- variation is constant, slow, and steady -- which is why I find this more plausible as a core mechanism of speciation. To give history some credit, there was no way to for people to know about these automata mechanisms until relatively recently.