Can man prove or absolutely deny the existence of a God? Whether the Bible's timeline during Genesis is accurate, or not, is a moot point, especially considering Science has a very loose grasp on Genesis. A creationist is just someone that believes that a God (or other supernatural being) created life, not someone that believes that the judeo-christian God created life.

The fact is we don't know the origin of life and there's no concrete proof supporting any explanation.

Could some invisible being in the sky, or universe, have created life? Sure, why not? One of the other explanations is all life just happened to come from mud. No proof for either explanation, but why do we immediately dismiss Creationism in favor of other ideas? Because you fear the idea of a 'God'? Because 'Creationism' is normally associated with the judeo-christian God?

All throughout history humans have held opinions on things that were horribly misguided. The earth was flat. The sun revolved around the planet. Things didn't exist unless they were within a direct line of sight. Objects in motion came to a stop because they got tired. We had absolutely no understanding of things like electromagnetism, gravity, nuclear forces, sound and space until the last several hundred years. Are you all suggesting that we're at the apex of our scientific discoveries? Have we really learned and discovered all there is to see and know? Last I checked, the standard model is still growing (and it has theoretical problems), we're still trying to explore space (and we haven't even ventured past the boundary of our solar system), and there are countless discoveries made in the chemical and biological realms each year. All things throughout scientific history exist before they're discovered, yet you fools are so naive to think there's no possibility of a God, and if there is, that it couldn't be responsible for life?

I'm confident that, one day, the origin of life will be proven. Until then, stop speaking in absolutes. Any absolute opinion on the matter requires a leap of faith -- whether a theist of atheist -- and you're stupid if you think otherwise.