Yeah, except it should read, "SCIENCE is built on a supposition...". The assumption that only natural causes are in play, for the restricted purpose of explaining and understanding natural processes, is common to ALL scientific theories. It is also EQUALLY common to all scientific theories. It is not one sinlge fraction of a degree more characteristic of evolution than of any other theory, law or principle.
Now, this may bother you; that science only considers natural cause. If so there's a solution for that, although a successful outcome is by no means guaranteed: Just develop a genuinely useful and successful theory that incorporates supernatural, non-natural, psychic, spiritualist (whatever) causes.
Science has never failed to accept a genuinely successful theory just because it violated what was then understood to be the nature of science. Instead the understanding of the nature of science was adjusted to accommodate the theory. This worked, for instance, for Newton's gravitation which appealed to an "occult" force that could act at a distance and transmit itself without physical impact between bodies.
What doesn't work, however, is whining. There are good reasons why scientists, even piously religious ones, think that science won't work with supernatural causes. (For instance, to be brief, if you can always invoke a miracle then any theory can always explain any result.) You have to DEMONSTRATE by example that supernatural science can work as science.
It is apparent to many Christians that the so called "science" of evolution is not applying to itself what you say it should, that is "adjusted to accommodate the (new) theory"
From fraud - The Great Piltdown Hoax - to a host of egregious practices and coverups - the scientific world is gradually retreating into a corner...and then lashing out at those who would dare question its methods and absolutism.
What Christians want is not the destruction of science or the scientific method - after all it was the coming of Christinity that unleashed the freedom of inquiry - but rather the breakup of conformist evolution---allowing a breath of fresh air into the discussion of origins and life on earth and the untethering of human origins to Darwin's ill formed theories.