I guess this is a silly question. I mean, shouldn't all PhD biologists know so much about genetics -- the theory of evolution that they can't see "diversity of life" coming about any other way? Then we have scientists like Michael Behe or neurosurgeon Michael Egnor telling us that evolution is a theory in crisis (basically).

How many biologists believe in evolution?  All but two of them (Michael Behe and Michael Egnor).  Seriously: the consensus is absolutely overwhelming.

(And by the way, Michael Behe believes in evolution, too: he just thinks that at a few critical junctures, a supernatural mechanism needed to be involved.  Despite his involvement with ID/creationism, Behe accepts that classic Darwinian descent-with-modification is the engine behind the great majority of organismal change through time.)

For a slightly pedantic response, I'm a biologist and I don't "believe" in evolution, I simply accept it as the best working hypothesis to explain the diversity of life on Earth. The evidence for evolution being the mechanism for speciation and variation is absolutely overwhelming - but we should always question our paradigms!

Behe and Egnor (and anyone else) are free to find fault with evolutionary theory, but without unequivocal evidence in support of opinions, they remain just that - opinions. Without support the supernatural is invoked because the supernatural provides a simple cultural - but not scientific -  mechanism for dealing with gaps in our knowledge. Since biologists are scientists they avoid invoking supernatural involvement in evolution, regardless of their personal beliefs. This doesn't mean that there aren't plenty of biologists who think there may be supernatural involvement, it just means that they are able to see that such opinions are not valid in a scientific forum because there is no evidence.

If someone ever comes up with a better theory to explain the diversity of life and the mechanisms that might drive that change, then biologists will jump on it. The fact is that 150 years on, no-one has ever found any evidence to contradict Darwinian / neo-Darwinian evolution (there are lots of kinds of evolution, but obviously this is really the only one we are referring to in modern biology). Just one *proven* contradiction would make us start again.

If someone managed to refute the theory of gravity (yes, the theory!) then a lot of physicists would be looking for some new data and theories very quickly. Its the same with all of science - evolution *may* not be right in every detail, but it is the best we have - it explains everything we know, and everything we have found since still fits into it (like sexual selection, genetics and all kinds of fossils). Until something better comes along (and thats not very likely) we will stick to it.

One thing I would say is that it is amazing how many people will talk about 'evolution' when they know so little about it. If you include my senior school education, I have studied evolutionary theory and practice one way or another for nearly 15 years, and I know just how ignorant I am about a great many aspects of it. Yet someone like Egnor (I don't like to name names, but you mentioned him!) who has never studied it formally in his life is happy to contradict the research of thousands upon thousands of scientists and experts without contributing a thing to the research.

Some confusion arise here because the colloquial meaning of the word theory and the scientific meaning are different.  A Theory in science is an accepted, hypothesis or model that is supported by evidence.  Colloquially the word theory is used to mean "a conjecture or hypothesis".  Gravity and Evolution are Theories in the scientific sense of the word.