No reason. I don't believe in creationism but there's no reason it can't exist alongside evolution because evolution doesn't even try to explain the formation of life, just what happens to it afterward. Unless you're a crazy person and believe the earth to be 6,000 years old, like my brother does. He's an idiot. I can't believe we share genetic code. I agree with both of you that they can co-exist. But I would note that the main evidence for creationism is the Old Testament, and no one seems to know exactly who came up with the concept. The problem in creationism arise from the literal interpretation of the Bible, that insists in seven days. for the Creation. Once you remove that, and take 7 days as seven (and seven in the Biblical sense, as many) as seven periods, there is plenty of room for evolution to fin into the Biblical story. That is why Catholicism, that does not interpret the Bible literally, has no major problems with evolution. But the Churches that take the Bible literally (certain Evangelical Churches, for example) they do. Regarding on how Biochemistry started, there are certain explanations. Under the primitive earth conditions, it is possible to synthesize urea and a few aminoacids from inorganic forms of nitrogen. Once you have nitrogen in organic molecules (like aminoacids, and urea), provided there is some water, it can go from there. Mind that we are talking here of periods of hundred of millions of years. How did we get from baseball to here?