1. The speed of light is 186,000 miles per second, and its distance in light years can trace the Earth back billions of years. (See the University of Michigan Library Database for further reading.)
2. History predates Creationism! Creationism places the world as 4,000-6,000 years of age, yet older archaeological documentation exists (such as the Chinese calendar) that it cannot explain away. (See Thinkquest.org: Evolution, Religion, and Creationism.)
3. There was no global flood. There isn't even enough water on earth for such a thing, nor could two of every animal fit on one ark. Haha, anyone else hear 'LIONS, TIGERS AND BEARS, OH MY!!!!' come to mind o.O?!?!?! (See Problems with a Global Flood by Mark Isaac for a more comprehensive list of evidence that discredits 'Young Earth' proponents; otherwise it would be the makings of a very, very long essay here :P.)
4. Evolution is the resounded conclusion of repeatedly confirmed facts. Like Electricity and Gravity, Evolution is a 'theory' and not a 'fact' because some of its details remain open to revision. As a science, therefore, it is based on irrefutable phenomena. Hence, Evolutionary biology will never just be 'overturned' someday when some loophole of "disproof" arises. On the contrary, it's currently the only theory the mainstream world's credible scientists legitimatize in their search to discover explanations about the origins of life.
To take a safely secure direction in handing out sound corroboration of this pinnacle-as-can-be fact—which ultimately remains, sheerly, standing at the legs of topmost notable Scientific principles within the entailed depths of the overarching debated matter here—I must wisely quote the scientists and experts detailing their various ever-asserted and reverified Evolutionary findings from The University of Berkeley respectively: "Scientists do not debate whether evolution (descent with modification) took place, but they do argue about how it took place. Details of the processes and mechanisms are vigorously debated. Anti-evolutionists hear the debates about how, HOW Evolution occurs and misinterpret them as debates about whether Evolution occurs. Evolution is sound science and is treated accordingly by scientists and scholars worldwide." (For further reading, check out the highly recommendable list of compelling responses to Evolution misconceptions on Berkeley's website.)
5. Creationism is a mathematical impossibility. Earth's population is now 7 billion, and humans simply could not have multiplied that fast in 4,000-6,000 years by any means, especially if everyone except a spare few were wiped out by the "Great Flood" after the first thousand years (or so)! And on top of that, if only two of each animal were left after this Biblical-alleged flood, the few remaining humans surely would have inevitably starved to death. In addition, all the well-documented diseases and famines that have wiped out millions throughout history further solidify creationism's mathematical fallacy. (For instance, The Black Death wiped out a third of Europe—approx. 100 million people.)
6. Creationism places Earth as the primary and center focus of "Creation". In reality we know the Universe was around many billions of years before the Earth began forming.
7. Please explain all the geological PROOF that dispels any such "Young Earth"
theory idea, please. (You can always check National Geographic's Archaeology page for new discoveries from ancient history.)
8. We are Evolving right now, everyday! We are taller, weigh more, facially differ (a bit, anyway), and even have slightly larger brains than our ancestors that lived just 2,000 years ago!
9. Heaven is mysteriously "gone" from the sky, where the Bible says it originated. I must quote Charlotte for this one: "God spends one-sixth of his entire creative effort (the second day) working on a solid firmament (Genesis 1: 6-8). This strange structure, which God calls heaven, is intended to separate the higher waters from the lower waters. This firmament, if it existed, would have been quite an obstacle to our space program."
10. "Time" as recorded in the Bible is a Paradoxical concept, IMPOSSIBLE to measure, and to no valid degree whatsoever historical in any way. I have my Rabbi of all people to thank for this one, respectively: for days to have passed on Earth, time must definitely have already existed, otherwise the concept of a 'day' as we know it is not possible. Nevertheless, Genesis withholds 'daytime' and 'nighttime' as part of existence until the fourth day: "God made two great lights—the greater light to govern the day and the lesser light to govern the night [,] to separate light from darkness. And there was evening, and there was morning—the fourth day" (Genesis 1: 16-19). Initially without fixed time, thus, in creationism Earth's lack of a 24-hour revolution of daytime and nighttime until the so-called 'fourth creation day' makes the length of preceded time (the first, second and third 'days') impossible to measure. (And even as proper time separation is loosely alluded to on 'Day Four', Genesis pseudo-claims there are two separate forces of light, one in day and the other in night, which we of course know is absolutely untrue.) Therefore, the preceding three creation "days" really could not at all have been days to the effect that human beings understand.
I mean come ON, people, the Bible calls a bat a bird for God's sake :P (Leviticus 11: 13-19)!