Do all scientists believe in evolution? If not, why not?

There are scientists who are not in a field of science closely associated with the biologic sciences, so they, like all of us, are free to accept or reject evolutionary evidence based on biases.  However, since the entire field of biology is now has evolution as its foundation, biologic scientists who rejects evolution are far and few between.  

But being a scientist in a field of study does not necessarily make that scientist infallible.  For instance, there is the biochemist Michael Behe who has refuted evolutionary theory by famously putting forward his argument for "irreducible complexity" which has been shown on a number of occasions to be wrong.