The reason some christians oppose evolution is that it relegates god's role in the development of life and in the development of man to the further reaches of biochemistry, to the presumed primordial soup in which the first self-replicating molecule complexes arose.
They are rightly concerned that this is the thin edge of the wedge: already god's role in cosmology is very distant, so much so that his involvement in it appears as implausible as humankind's presence in the cosmos is insignificant.
If they were to grant the truth of evolution, god is displaced of most his role in Life too, and suffers another large demotion in the scope of things he can reasonably be seen to be in charge of.
Furthermore, the ascent of science is a problem for all religions that require one to go on faith (which is nothing be belief in the incredible, in the absence of any substantiating evidence). This is because the advancing armies of science, with its seemingly pig-headed insistence on evidence, have beat the cr*p out of other belief systems that don't rest on evidence (astrology, faith healing, soothsaying etc. etc.), and they fear that religion, the granddaddy of unsubstantiated belief systems, will suffer the same fate.
The sad (from their perspective) truth is that they are right. The best they can do at the moment, as many on slashdot seem to do, is to tacitly concede the demotion in god's role that Darwin ushered in, issuing platitudes like "religion and science can learn from each other, and indeed, support each other." Which, of course, is rubbish -- science, in the main, has nothing to learn from religion.
For those of us who do believe in evolution, we know that we have a far stronger force than an imagined and imaginary god on our side: evidence. The only way we can win this one is if we keep insisting that only way to resolve conflicting belief systems is by evidence, and by educating the other side on the evidence well enough that they come to the same conclusions the rest of us have.
And as for the implication that this has on god's role in the scheme of thing, well, god help them.
