The Talk Origins FAQ give a fairly good overview. From my understanding, Theistic evolutionists accept mainstream science as valid and does not allow acceptence of evidence and science to interfere with their understanding of their faith or their God as valid.
http://www.talkorigins.org/faqs/faq-god.html
Q1. Doesn't evolution contradict religion?
Not always. Certainly it contradicts a literal interpretation of the first chapter of Genesis, but evolution is a scientific principle, like gravity or electricity.
To scientifically test a religious belief one first must find some empirical test that gives different results depending on whether the belief is true or false. These results must be predicted before hand, not pointed to after the fact.
Most religious beliefs don't work this way. Religion usually presupposes a driving intelligence behind it, and an intelligent being is not always predictable.
Since experiments judging religious beliefs cannot have predictable results, and may give different results under the same circumstances it is not open to scientific inquiry. St. Augustine commented on this in _The Literal Meaning of Genesis_.
Some religious beliefs do make predictions. These predictions can be tested. If a religious belief fails a test, it is the test that contradicts that religious belief. The theory which makes the correct prediction should have nothing to say on the matter. This does not mean that scientists don't sometimes make the mistake of saying a theory contradicts something.
Q2. Isn't evolution a religion?
E
volution is based on the scientific method.
There are tests that can determine whether or not the theory is correct as it stands, and these tests can be made. Thousands of such tests have been made, and the current theories have passed them all. Also, scientists are willing to alter the theories as soon as new evidence is discovered. This allows the theories to become more and more accurate as research progresses.
Most religions, on the other hand, are based on revelations, that usually cannot be objectively verified. They talk about the why, not the how. Also, religious beliefs are not subject to change as easily as scientific beliefs. Finally, a religion normally claims an exact accuracy, something which scientists know they may never achieve.
Some people build up religious beliefs around scientific principles, but then it is their beliefs which are the religion. This no more makes scientific knowledge a religion than painting a brick makes it a bar of gold.
So the answer is no, evolution is no more a religion than any other scientific theory.