I told you what it is: the changing of one species or a part of it into or more other species. The gut of the science is trying to figure out how it works. One of the major problems evolution has is that it's actually not a distinct science in itself, it's a place where multiple sciences (primarily paleontology and genetics) meet, changes in either science create changes in evolutionary thought. And all three are incredibly young sciences.
Funny first you want it in one simple sentence, then you want specifics. Thus proving that what you really want is to remain unchallenged.
Much like the principle creeds of a religion statements of scientific theor are just the beginning. The meat of the matter isn't in the creed or the theory, but the meaning of the creed or theory and how it works. there is no evolutionism that's YOUR invention to turn a science into a quasi-religion. You've had the precis of the theory posted to you many times already, but that's just the grossly oversimplified view that can be expressed quickly and holds none of the meat of the matter; much like someone saying Christianity is worship of this guy that died and was reborn, yeah that's part of it but there's so much more.
The only thing we can see that causes evolution is environment, changes to the world animals live in (something we know is constant) and competition between living things for the same resources (something that's even more constant). Things seek an advantage and they change, this makes other things change or die. One of the creeds of the Marine Corps is adapt and overcome, that's the cause of evolution, adaptations to overcome. Now those adaptations could be guided by a devine hand, there's nothing that rules such out. One thing science learned a long time ago is that if there is a God He's really orderly and likes to do things in a way that they're self sufficient, self perpetuating, and can eventually be quantified and explained. That's why Ptolemy lost out, his model was high maintenance and required constant deific intervention, which doesn't match how anything else works.
But again, once again, let's say that I grant you this - fact - however you understand it, or define it, or work with it, etc. I wondered if there was some theory you might also be working through to help explain this odd fact?
you want it in one simple sentence
Make it a long sentence. Make it two. Make it three. When describing basic particle physics, you can cut to the gist quickly. But perhaps not in one, single sentence. But you don't have to write a full chapter, either, to explain the basic definitions. If you have theory for your fact, I suspect it's not nearly as complicated as particle physics. Surely you can say what you mean, succinctly, and knowing that no reasonable person would confuse such a statement with the detailed sum of knowledge of the field. Put the herring back in the can and answer the question.
The meat of the matter isn't in the creed
That's precisely what the Creed is. That's the point. That's the basis, the norm, the standard, the very minimum which one must entirely confess in each point or else consider oneself on the outside looking in. As for what the words and phrases mean - yes, there is further explanation. Since it is not merely religion, but Revelation, the explanation is voluminous and reflects some of the most intense personal moments in people's lives through the ages.
Christianity is
But you know what Christianity is. It's been explained, succinctly, definitively - in the four principal Creeds of The Church. That's the point. You're not getting this.
an advantage
Not true. It could be a disadvantage that proves ultimately irrelevant to this vague operation of evolutionist forces. Until you can say what causes - evolution - you can't say much else about it. What do you think causes it, specifically? Lay it out, as one who understands. Those who understand, in any field, can explain it cleanly, and succinctly, as you might well know yourself.
constant deific intervention, which doesn't match how anything else works.
But how do you test that? You say God does not intervene, even every hour, not even every indivisible unit of time, continually that is. But how do you know that? Has science put God to the test? And if so, is that science?