<---Biology major, focus: Human Biology and Genetics
To me, macroevolution is borderline undeniable. We might not see mamallian macroevolution on a daily basis because it takes too long (longer than our scientific history), but the evidence is in plant evolution. Plants speciate regularly, withing a year. We have seen it and it has been documented, speciation in process.
I further believe (staying in mind with actual evidence) that there was no "creation" as stated in the Bible.
HOWEVER, the one thing that NO ONE can definitively argue (not even the great Darwin himself) is how did it all get there? Dating back to string theory and pre-Big Boom moments, no one can say if a god did or did not put matter there or where matter came from. It is just as logical to say that "matter has always existed" as it is to say "a god always existed".
I consider myself a fairly informed atheist, but I am absolutely stumped when it comes to pre-bigbang era. I absolutely have no clue. It is the one place I could accept a creator (but of the "hands off" style).
It's foolish to try to argue either way. Even more, it's non-scientific to say you know definitively either way. There are VERY few definitive answers in science. Does that make the science weaker than faith? Science is set up so everything is always questioned.
Just to clarify, there seems to be some confusion as to what macroevolution actually is. Macroevolution, simply, revolves around the idea that one species can, through evolution, become another species. The tricky part in putting this all together is the definition of the word "species". I think it's best said as, "A reproductively isolated aggregate of interbreeding organisms." Keys being, two different species are different in morphological variations and they can produce fertile offspring. It is a theory and is designed so it really can never be proved (try applying math to evolution, that isn't statistics).
Ex. A lion and tiger can breed, but are not the same species because a) they are morphologically different and b) their offspring is sterile.
Another decent definition: "a population of individuals that are alike, are able to breed and produce fertile offspring under natural conditions"