The smallest living cell on earth has a DNA string of some 1 million pairs of DNA and has 600 genes. [...] The chances of such an arangement of DNA arising by sheer chance are 4 to the 250'000th power, and that's generous. [...]
The problem though is even worse than that. Not only do you need two strings of DNA perfectly matched to have life, but you also need a cell so the DNA code can get the material to sustain that life. It's therefore a chicken-and-egg problem. [...]
Add to this problem that for the first life to have been the progenator of all life on earth, it necessarily needs to have been pretty much the same as all life now on earth, otherwise it couldn't have been the source of all life we now know.
What this means is this: the first life on earth had to require oxygen in order for them to be the ancestors of oxygen-requiring life, that's common sense. [...]